Not much is known about him, except that he is a Default family member labeled as "insane."
In "Blinking Light," a portrait of him is shown inside Gart's office, being mentioned that Crazy Cousin Gizmo was in line to take care of the factory whenever Gart was absent. However, due to his cousin's insanity and the list of possible family members, the supervisor reluctantly chose Robot.
He makes his first actual appearance in "Apartment 3 1/2" when Robot enlists his help to aid Monster Krumholtz in what he had assumed was a type of Schizophrenia when Monster claims that his "imaginary friend," Fuzzy Slippers, is real. However, Crazy Cousin Gizmo's advice seemed somewhat redundant as his own hallucinations got in the way of solving the problem; his advice turned hopeless when Monster mentioned that Fuzzy Slippers emitted "disappearing confetti," resorting in Crazy Cousin Gizmo (ironically) calling it insane.
His insanity is usually quite too intimidating for Robot to handle, usually frightening him to the point where Robot is desperate to run off. However, in "The Party," it is revealed how close they seem to be, to the point where Robot stands up to his mother when she demands Crazy Cousin Gizmo thrown out of Gart's party, marking him a family member just as shunned as Robot, if not worse. Robot realizes that he and his cousin aren't that different at all, and finally sees how original and unique Crazy Cousin Gizmo is despite his schizophrenia, even mellowing to play along in seeing his invisible "fiancée," Princess Invisible, resorting to dancing with "her," not caring about embarrassing himself in front of everyone.
He often refers to Robot as "Sane Cousin Robot," reciprocating the nicknaming of himself. He cares deeply about him, even calling him his favorite cousin, as he may be aware that he is greatly disliked by the rest of his family. It is suspected that Robot may be the only family member who's ever bothered to visit him at the mental asylum. Apart from Robot, he seems to have a very good relationship with Monster, as they have very similar personalities, with the addition of embracing their imaginations.
Blinking Light (cameo)
It is not until "Apartment 3 1/2" that we learn he has Schizophrenia, a mental case of seeing and interacting with people who aren't real. It is unsure how he began the mental disorder, or how long he has been in the mental instiution because of it, but according to Gart in "Blinking Light," it may have been around the time that took place years after Gart took over the Blinking Light Factory.
- He actually ate Robot's antenna after suspecting it of being a tracking device (which, apparently, he was right about) in his second episode, "The Party."
- His attire greatly resembles Willy Wonka.
- His personality almost seems similar to the Mad Hatter from the Disney movie, Alice in Wonderland.
- It is uncertain who his parents are, as they had not been seen nor mentioned in "The Party." However, he was interacting with his aunt, Arpa Default, in that episode.
- He is the first Mechanical, and one of the few characters in the whole show, to be seen with shoes and one of the few characters to be shown with teeth as well as an actual brain. The only other known character is Nessie.
- He is the second character to possess a mental disorder; Punch Morley and his short-term memory loss is featured as the first.
- His physical appearance is somewhat similar to that of Hal Worth-A-Ton.
- His active imagination seems similar to Goo from Foster's Home for Imaginary Friends.
- His usually cheerful mood resembles Pops from Regular Show, although Pops clearly lacks Gizmo's schizophrenia.
- Interesting to note is that they both wear sophisticated and gentleman-like attire.