Captain Peanutbutter is a Labrador Retriever and the brother of Mr. Peanutbutter. He appears in two episodes in season three. He has two unnamed sons. In Old Acquaintance, he informs Mr. Peanutbutter that he has a twisted spleen that is successfully removed in It's You.
He is voiced by " Weird Al Yankovic".
He has a great and healthy relationship for his younger brother Mr Peanutbutter, by whom he is older than by five minutes.