The Narrator's Brother is brother of The Narrator. He is quite like The Narrator, although he is a bit more dramatic. He is the Narrator's identical twin brother, only 20 seconds older.
The Narrator's Brother appeared in the episode Mecha-Mouse.
At the end of Chuck's Brother, The Narrator mentions that he should call his brother Glen, the sportscaster. It is uncertain whether or not Glen refers to a second brother, or if it refers to the same brother.