diff --git a/amanuensis/backend/character.py b/amanuensis/backend/character.py
new file mode 100644
index 0000000..c8f04da
--- /dev/null
+++ b/amanuensis/backend/character.py
@@ -0,0 +1,64 @@
+"""
+Character query interface
+"""
+
+from sqlalchemy import select, func
+
+from amanuensis.db import *
+from amanuensis.errors import ArgumentError
+
+
+def create(
+    db: DbContext,
+    lexicon_id: int,
+    user_id: int,
+    name: str,
+    signature: str) -> Character:
+    """
+    Create a new character for a user.
+    """
+    # Verify argument types are correct
+    if not isinstance(lexicon_id, int):
+        raise ArgumentError('lexicon_id')
+    if not isinstance(user_id, int):
+        raise ArgumentError('user_id')
+    if not isinstance(name, str):
+        raise ArgumentError('name')
+    if signature is not None and not isinstance(signature, str):
+        raise ArgumentError('signature')
+
+    # Verify character name is valid
+    if not name.strip():
+        raise ArgumentError('Character name cannot be blank')
+
+    # If no signature is provided, use a default signature
+    if not signature or not signature.strip():
+        signature = f'~{name}'
+
+    # Check that the user is a member of this lexicon
+    mem: Membership = db(
+        select(Membership)
+        .where(Membership.user_id == user_id)
+        .where(Membership.lexicon_id == lexicon_id)
+    ).scalar_one_or_none()
+    if not mem:
+        raise ArgumentError('User is not a member of lexicon')
+
+    # Check that this user is below the limit for creating characters
+    num_user_chars = db(
+        select(func.count(Character.id))
+        .where(Character.lexicon_id == lexicon_id)
+        .where(Character.user_id == user_id)
+    ).scalar()
+    if mem.lexicon.character_limit is not None and num_user_chars >= mem.lexicon.character_limit:
+        raise ArgumentError('User is at character limit')
+
+    new_character = Character(
+        lexicon_id=lexicon_id,
+        user_id=user_id,
+        name=name,
+        signature=signature,
+    )
+    db.session.add(new_character)
+    db.session.commit()
+    return new_character
diff --git a/tests/test_character.py b/tests/test_character.py
new file mode 100644
index 0000000..26134ed
--- /dev/null
+++ b/tests/test_character.py
@@ -0,0 +1,73 @@
+import pytest
+
+from amanuensis.db import *
+import amanuensis.backend.character as charq
+from amanuensis.errors import ArgumentError
+
+
+def test_create_character(db: DbContext, lexicon_with_editor, make_user):
+    """Test creating a character."""
+    lexicon, user = lexicon_with_editor
+    kwargs = {
+        'db': db,
+        'user_id': user.id,
+        'lexicon_id': lexicon.id,
+        'name': 'Character Name',
+        'signature': 'Signature',
+    }
+
+    # Bad argument types
+    with pytest.raises(ArgumentError):
+        charq.create(**{**kwargs, 'name': b'bytestring'})
+    with pytest.raises(ArgumentError):
+        charq.create(**{**kwargs, 'name': None})
+    with pytest.raises(ArgumentError):
+        charq.create(**{**kwargs, 'signature': b'bytestring'})
+
+    # Bad character name
+    with pytest.raises(ArgumentError):
+        charq.create(**{**kwargs, 'name': ' '})
+
+    # Signature is auto-populated
+    char = charq.create(**{**kwargs, 'signature': None})
+    assert char.signature is not None
+
+    # User must be in lexicon
+    new_user = make_user()
+    with pytest.raises(ArgumentError):
+        charq.create(**{**kwargs, 'user_id': new_user.id})
+
+
+def test_character_limits(db: DbContext, lexicon_with_editor):
+    """Test lexicon settings limiting character creation."""
+    lexicon: Lexicon
+    user: User
+    lexicon, user = lexicon_with_editor
+
+    # Set character limit to one and create a character
+    lexicon.character_limit = 1
+    db.session.commit()
+    char1 = charq.create(db, lexicon.id, user.id, 'Test Character 1', signature=None)
+    assert char1.id, 'Failed to create character 1'
+
+    # Creating a second character should fail
+    with pytest.raises(ArgumentError):
+        char2 = charq.create(db, lexicon.id, user.id, 'Test Character 2', signature=None)
+        assert char2
+
+    # Raising the limit to 2 should allow a second character
+    lexicon.character_limit = 2
+    db.session.commit()
+    char2 = charq.create(db, lexicon.id, user.id, 'Test Character 2', signature=None)
+    assert char2.id, 'Failed to create character 2'
+
+    # Creating a third character should fail
+    with pytest.raises(ArgumentError):
+        char3 = charq.create(db, lexicon.id, user.id, 'Test Character 3', signature=None)
+        assert char3
+
+    # Setting the limit to null should allow a third character
+    lexicon.character_limit = None
+    db.session.commit()
+    char3 = charq.create(db, lexicon.id, user.id, 'Test Character 3', signature=None)
+    assert char3.id, 'Failed to create character 3'