In 1936, Disney went meta. In the cartoon short Mickey’s Rival, we are introduced to a pompous character named Mortimer who becomes a rival for Minnie Mouse’s attention.
Why was this meta? Walt Disney originally wanted to name his famous mouse Mortimer. After asking his wife what she thought, she felt the name was pompous and suggested Mickey Mouse instead. When the idea was pitched for an annoying rival for Mickey, Walt had the perfect name- Mortimer Mouse.