diff --git a/CHANGELOG.yaml b/CHANGELOG.yaml
index e731ec78..37a91c0c 100644
--- a/CHANGELOG.yaml
+++ b/CHANGELOG.yaml
@@ -1,5 +1,6 @@
 0.38.0.dev:
   features:
+  - "Player Character Toggle: Added a Make Player Character / Unmark as Player action to the World Editor character editor. Promoting a non-player character makes them the player and automatically demotes the previous player (if any) to an AI actor — the previous player stays active in the scene. Unmarking the current player flips them to AI without requiring a replacement, leaving the scene with no explicit player. Promoting an inactive character also activates them."
   - "Message Revision History: Regenerated AI messages now show a paginator above the message body. Click the arrows to browse previous regenerations; the version you're viewing becomes the canonical one the AI continues from. Lives in the browser session only."
   improvements:
   - "Message Revision History: Continuing a character or narrator message now creates a navigable revision entry tagged 'Continued', alongside the existing regenerate entries. The pre-continuation text is reachable via the paginator arrows. Narrator messages also gain the Continue action on the hover toolbar to match the character-message flow."
diff --git a/src/talemate/character.py b/src/talemate/character.py
index dacfb3d3..f0743ef8 100644
--- a/src/talemate/character.py
+++ b/src/talemate/character.py
@@ -25,6 +25,7 @@ __all__ = [
     "VoiceChangedEvent",
     "deactivate_character",
     "activate_character",
+    "set_character_is_player",
     "set_voice",
 ]
 
@@ -724,6 +725,59 @@ async def activate_character(scene: "Scene", character: Union[str, "Character"])
     scene.active_characters.append(character.name)
 
 
+async def _demote_player_to_actor(scene: "Scene", character: "Character"):
+    """Flip is_player off and, if active, swap the Player actor for a plain Actor.
+
+    Caller must ensure `character` is currently the player (or is being
+    unmarked); this helper does not re-check the flag.
+    """
+    character.is_player = False
+    if scene.character_is_active(character):
+        new_actor = scene.Actor(character, instance.get_agent("conversation"))
+        await scene.add_actor(new_actor, commit_to_memory=False)
+
+
+async def set_character_is_player(
+    scene: "Scene", character: Union[str, "Character"], is_player: bool
+):
+    """
+    Sets or clears a character's player status. At most one character may be
+    the player at any time, so promoting a non-player demotes the existing
+    player (if any) to an AI Actor. Active characters get their actor swapped
+    in place; inactive characters being promoted are auto-activated.
+
+    Arguments:
+        scene: The scene the character lives in.
+        character: The character to update. Can be a name or a Character object.
+        is_player: True to mark as player, False to unmark.
+    """
+    if isinstance(character, str):
+        character = scene.get_character(character)
+
+    if not character:
+        log.error("character not found")
+        return
+
+    if character.is_player == is_player:
+        return
+
+    if is_player:
+        current_player = scene.get_explicit_player_character()
+        if current_player is not None and current_player is not character:
+            await _demote_player_to_actor(scene, current_player)
+
+        if scene.character_is_active(character):
+            # add_actor sets is_player=True when the new actor is a Player
+            new_actor = scene.Player(character, None)
+            await scene.add_actor(new_actor, commit_to_memory=False)
+        else:
+            # activate_character reads is_player to pick the Player class
+            character.is_player = True
+            await activate_character(scene, character)
+    else:
+        await _demote_player_to_actor(scene, character)
+
+
 async def set_voice(character: "Character", voice: Voice | None, auto: bool = False):
     character.voice = voice
     emission: VoiceChangedEvent = VoiceChangedEvent(
diff --git a/src/talemate/server/world_state_manager/character.py b/src/talemate/server/world_state_manager/character.py
index 7d0266b7..b4cc6854 100644
--- a/src/talemate/server/world_state_manager/character.py
+++ b/src/talemate/server/world_state_manager/character.py
@@ -63,6 +63,13 @@ class RenameCharacterFolderPayload(pydantic.BaseModel):
     new_name: str
 
 
+class SetCharacterIsPlayerPayload(pydantic.BaseModel):
+    """Payload for setting a character's player status."""
+
+    name: str
+    is_player: bool
+
+
 class CharacterMixin:
     """Mixin adding websocket handlers for character voice assignment."""
 
@@ -256,6 +263,39 @@ class CharacterMixin:
         await self.signal_operation_done()
         self.scene.emit_status()
 
+    async def handle_set_character_is_player(self, data: dict):
+        """Toggle a character's player status.
+
+        Expected payload
+        -----------------
+        {
+            "type": "world_state_manager",
+            "action": "set_character_is_player",
+            "name": "<character name>",
+            "is_player": true | false
+        }
+        """
+        try:
+            payload = SetCharacterIsPlayerPayload(**data)
+        except pydantic.ValidationError as e:
+            log.error("Invalid payload for set_character_is_player", error=e)
+            await self.signal_operation_failed(str(e))
+            return
+
+        character = self.scene.get_character(payload.name)
+        if not character:
+            await self.signal_operation_failed("Character not found")
+            return
+
+        await self.world_state_manager.set_character_is_player(
+            payload.name, payload.is_player
+        )
+
+        await self.handle_get_character_list({})
+        await self.handle_get_character_details({"name": payload.name})
+        await self.signal_operation_done()
+        self.scene.emit_status()
+
     async def handle_rename_character_folder(self, data: dict):
         """Bulk-rename a folder across every character currently assigned to it.
 
diff --git a/src/talemate/world_state/manager.py b/src/talemate/world_state/manager.py
index c1ce0e0e..bbaac5f5 100644
--- a/src/talemate/world_state/manager.py
+++ b/src/talemate/world_state/manager.py
@@ -5,7 +5,12 @@ import structlog
 
 import talemate.world_state.templates as world_state_templates
 from talemate.agents.tts.util import get_voice
-from talemate.character import activate_character, deactivate_character, set_voice
+from talemate.character import (
+    activate_character,
+    deactivate_character,
+    set_character_is_player,
+    set_voice,
+)
 from talemate.instance import get_agent
 from talemate.emit import emit
 from talemate.world_state import (
@@ -991,6 +996,15 @@ class WorldStateManager:
         """
         await deactivate_character(self.scene, character_name)
 
+    async def set_character_is_player(self, character_name: str, is_player: bool):
+        """
+        Sets or clears a character's player status.
+
+        See :func:`talemate.character.set_character_is_player` for the full
+        contract.
+        """
+        await set_character_is_player(self.scene, character_name, is_player)
+
     async def create_character(
         self,
         generate: bool = True,
diff --git a/talemate_frontend/src/components/WorldStateManagerCharacter.vue b/talemate_frontend/src/components/WorldStateManagerCharacter.vue
index 0c594481..9e1b9a3a 100644
--- a/talemate_frontend/src/components/WorldStateManagerCharacter.vue
+++ b/talemate_frontend/src/components/WorldStateManagerCharacter.vue
@@ -131,6 +131,27 @@
 
                                 <v-divider></v-divider>
 
+                                <!-- TOGGLE PLAYER CHARACTER -->
+                                <div>
+                                    <v-list-item v-if="!character.is_player">
+                                        <v-tooltip max-width="300" :text="`Mark ${character.name} as the player character. The current player character (if any) will be demoted to an AI actor.`">
+                                            <template v-slot:activator="{ props }">
+                                                <v-btn @click.stop="setIsPlayer(true)" v-bind="props" variant="tonal" block color="info" prepend-icon="mdi-account-star">Make Player Character</v-btn>
+                                            </template>
+                                        </v-tooltip>
+                                    </v-list-item>
+
+                                    <v-list-item v-else>
+                                        <v-tooltip max-width="300" :text="`Unmark ${character.name} as the player character. They will become an AI actor and remain in the scene.`">
+                                            <template v-slot:activator="{ props }">
+                                                <v-btn @click.stop="setIsPlayer(false)" v-bind="props" variant="tonal" block color="info" prepend-icon="mdi-account-off-outline">Unmark as Player</v-btn>
+                                            </template>
+                                        </v-tooltip>
+                                    </v-list-item>
+                                </div>
+
+                                <v-divider></v-divider>
+
                                 <!-- DEACTIVATE CHARACTER -->
                                 <div>
                                     <v-list-item v-if="character.active">
@@ -563,6 +584,14 @@ export default {
                 name: this.character.name,
             }));
         },
+        setIsPlayer(isPlayer) {
+            this.getWebsocket().send(JSON.stringify({
+                type: 'world_state_manager',
+                action: 'set_character_is_player',
+                name: this.character.name,
+                is_player: isPlayer,
+            }));
+        },
         visualizeCharacter() {
             this.coverImageBusy = true;
             this.getWebsocket().send(JSON.stringify({
diff --git a/tests/test_character_is_player.py b/tests/test_character_is_player.py
new file mode 100644
index 00000000..23689cc4
--- /dev/null
+++ b/tests/test_character_is_player.py
@@ -0,0 +1,203 @@
+"""
+Tests for ``WorldStateManager.set_character_is_player`` — toggling a character's
+player status from the World State Manager.
+
+Design contract:
+- At most one character may be the player at any time.
+- Promoting a non-player demotes the existing player (if any) to a plain
+  AI Actor; the previous player stays active in the scene.
+- Active characters get their actor swapped in place (Actor↔Player).
+- Inactive characters being promoted are auto-activated.
+- No-ops (same state, unknown name) must not raise.
+"""
+
+import pytest
+
+from conftest import MockScene, bootstrap_scene
+from talemate.character import Character
+from talemate.tale_mate import Actor, Player
+from talemate.world_state.manager import WorldStateManager
+
+
+@pytest.fixture
+def scene():
+    mock_scene = MockScene()
+    bootstrap_scene(mock_scene)
+    return mock_scene
+
+
+@pytest.fixture
+def manager(scene):
+    return WorldStateManager(scene)
+
+
+def _add_active_npc(scene, name: str) -> Character:
+    """Active AI character — wrapped in a plain Actor, registered in both
+    ``scene.actors`` and ``scene.active_characters`` to mirror production.
+    """
+    character = Character(name=name, is_player=False)
+    actor = Actor(character=character, agent=None)
+    scene.actors.append(actor)
+    scene.character_data[character.name] = character
+    if character.name not in scene.active_characters:
+        scene.active_characters.append(character.name)
+    return character
+
+
+def _add_active_player(scene, name: str) -> Character:
+    """Active player character — wrapped in a Player actor."""
+    character = Character(name=name, is_player=True)
+    actor = Player(character=character, agent=None)
+    scene.actors.append(actor)
+    scene.character_data[character.name] = character
+    if character.name not in scene.active_characters:
+        scene.active_characters.append(character.name)
+    return character
+
+
+def _add_inactive_character(
+    scene, name: str, is_player: bool = False
+) -> Character:
+    """Inactive character — present in ``character_data`` but without an
+    actor and not in ``active_characters``.
+    """
+    character = Character(name=name, is_player=is_player)
+    scene.character_data[character.name] = character
+    if character.name in scene.active_characters:
+        scene.active_characters.remove(character.name)
+    return character
+
+
+def _actor_for(scene, name: str):
+    for actor in scene.actors:
+        if actor.character is not None and actor.character.name == name:
+            return actor
+    return None
+
+
+class TestSetCharacterIsPlayer:
+    @pytest.mark.asyncio
+    async def test_promote_active_npc_when_no_player(self, scene, manager):
+        npc = _add_active_npc(scene, "Alice")
+        assert scene.get_explicit_player_character() is None
+
+        await manager.set_character_is_player("Alice", True)
+
+        assert npc.is_player is True
+        assert isinstance(_actor_for(scene, "Alice"), Player)
+        assert scene.get_explicit_player_character() is npc
+
+    @pytest.mark.asyncio
+    async def test_promote_active_npc_demotes_existing_player(self, scene, manager):
+        prev = _add_active_player(scene, "Hero")
+        npc = _add_active_npc(scene, "Bob")
+
+        await manager.set_character_is_player("Bob", True)
+
+        # New player is correctly promoted
+        assert npc.is_player is True
+        assert isinstance(_actor_for(scene, "Bob"), Player)
+        # Previous player is demoted to plain Actor, still active
+        assert prev.is_player is False
+        prev_actor = _actor_for(scene, "Hero")
+        assert prev_actor is not None
+        assert isinstance(prev_actor, Actor)
+        assert not isinstance(prev_actor, Player)
+        assert "Hero" in scene.active_characters
+        # Only one explicit player remains
+        assert scene.get_explicit_player_character() is npc
+
+    @pytest.mark.asyncio
+    async def test_promote_inactive_character_auto_activates(self, scene, manager):
+        ghost = _add_inactive_character(scene, "Ghost")
+        assert "Ghost" not in scene.active_characters
+        assert _actor_for(scene, "Ghost") is None
+
+        await manager.set_character_is_player("Ghost", True)
+
+        assert ghost.is_player is True
+        # Should have been activated as a Player
+        assert "Ghost" in scene.active_characters
+        assert isinstance(_actor_for(scene, "Ghost"), Player)
+        assert scene.get_explicit_player_character() is ghost
+
+    @pytest.mark.asyncio
+    async def test_promote_inactive_demotes_existing_active_player(
+        self, scene, manager
+    ):
+        prev = _add_active_player(scene, "Hero")
+        ghost = _add_inactive_character(scene, "Ghost")
+
+        await manager.set_character_is_player("Ghost", True)
+
+        # Inactive target activated as Player
+        assert ghost.is_player is True
+        assert "Ghost" in scene.active_characters
+        assert isinstance(_actor_for(scene, "Ghost"), Player)
+        # Previous active player demoted but still active
+        assert prev.is_player is False
+        assert "Hero" in scene.active_characters
+        assert isinstance(_actor_for(scene, "Hero"), Actor)
+        assert not isinstance(_actor_for(scene, "Hero"), Player)
+
+    @pytest.mark.asyncio
+    async def test_demote_active_player(self, scene, manager):
+        player = _add_active_player(scene, "Hero")
+
+        await manager.set_character_is_player("Hero", False)
+
+        assert player.is_player is False
+        actor = _actor_for(scene, "Hero")
+        assert actor is not None
+        assert isinstance(actor, Actor)
+        assert not isinstance(actor, Player)
+        # Still active in the scene
+        assert "Hero" in scene.active_characters
+        # No explicit player remains
+        assert scene.get_explicit_player_character() is None
+
+    @pytest.mark.asyncio
+    async def test_set_same_state_is_noop_for_player(self, scene, manager):
+        player = _add_active_player(scene, "Hero")
+        original_actor = _actor_for(scene, "Hero")
+
+        await manager.set_character_is_player("Hero", True)
+
+        assert player.is_player is True
+        # Actor identity preserved — no unnecessary swap
+        assert _actor_for(scene, "Hero") is original_actor
+
+    @pytest.mark.asyncio
+    async def test_set_same_state_is_noop_for_npc(self, scene, manager):
+        npc = _add_active_npc(scene, "Alice")
+        original_actor = _actor_for(scene, "Alice")
+
+        await manager.set_character_is_player("Alice", False)
+
+        assert npc.is_player is False
+        assert _actor_for(scene, "Alice") is original_actor
+
+    @pytest.mark.asyncio
+    async def test_unknown_character_is_noop(self, scene, manager):
+        existing = _add_active_npc(scene, "Alice")
+
+        # Must not raise
+        await manager.set_character_is_player("DoesNotExist", True)
+
+        # Unrelated state is untouched
+        assert existing.is_player is False
+        assert scene.get_explicit_player_character() is None
+
+    @pytest.mark.asyncio
+    async def test_demote_inactive_player_just_flips_flag(self, scene, manager):
+        """An inactive character that was marked as player (e.g. waiting to be
+        re-activated) can be unmarked without being touched in the scene.
+        """
+        dormant = _add_inactive_character(scene, "Dormant", is_player=True)
+
+        await manager.set_character_is_player("Dormant", False)
+
+        assert dormant.is_player is False
+        # Still inactive, still no actor
+        assert "Dormant" not in scene.active_characters
+        assert _actor_for(scene, "Dormant") is None