|Residence||Nega-Turner House, Nega-Dimmsdale, Nega-California, U.N.-S.N.-A.|
|First appearance||Nicktoons: The Heroes Meet Their Match|
Jeff is the first invention built by Nega-Timmy.
He is grey. He is an old robot that is about as tall as a normal adult is. He has one wheel for movement, two arms, a cylindrical body, a cylindrical head on a tube neck, two circular eyes, and an antenna in the middle of the top of his head.
Much like his creator, Fairly Odd Parents "episodes" will also feature him.
Because he has lived so long, he is sarcastic and cynical.
Nega-Timmy built Jeff when Nega-Timmy was one years old in 1993. He is Nega-Timmy's first invention.
At the time, Nega-Timmy did not know about the "Nega-" prefix, which made him name his robot "Jeff" and not "Nega-Jeff". When he did find out about the "Nega-" prefix, the Nega-Turners had established the robot's name, so it stuck.