Grampy

Professor Grampy is an animated cartoon character appearing in the "Betty Boop" series of shorts produced by Max Fleischer and released by Paramount Pictures. He appeared in nine of the later "Betty Boop" cartoons beginning with "Betty Boop and Grampy" (1935). He had a starring role in the "Color Classic," "Christmas Comes But Once A Year" (1936).
Grampy is an ever-cheerful and energetic senior citizen with a bald, dome-shaped head, white beard, and a black nose. One author speculates that Grampy's character design may suggest he is Ko-Ko the Clown in retirement. His primary activities include singing, dancing and building Rube Goldberg-esque devices out of ordinary household items. When presented with an unexpected new problem, he will put on his thinking cap (a mortarboard with a lightbulb on top). In short order the lightbulb lights up and Grampy builds a new gadget to solve the problem. The character was possibly based upon Max's brother, Charles. He was an inventor. One of his
creations was the clawing device that (in 2021) is still omnipresent in arcades and standalone
toys.
It is not clear whether Grampy is actually related to Betty Boop, because everyone calls him "Grampy" and he seems to be equally affectionate to almost everyone he meets. There is also some inconsistency as to living arrangements. In some cartoons like "Betty Boop and Grampy" and "House Cleaning Blues" he and Betty live in separate houses. However, in "The Impractical Joker" he lives in an upper floor. 
The identity of Grampy's voice actor has been subject to debate. The Fleischer Studios credits Popeye voice actor Jack Mercer as the voice of Grampy, while the character's article on Don Markstein's Toonopedia indicated that standard reference sources didn't name Grampy's voice actor, aside from some isolated mentions crediting Everett Clark for the role.
Grampy appeared in nine of the later "Betty Boop" cartoons in the mid-1930s, often having a larger role than Betty. He also made one appearance without Betty, in the 1936 "Color Classics" short "Christmas Comes But Once a Year".