James "Jimmy" Nixon McGarfield was the Fourth Grade President-For-Life at Gallagher Elementary School.
He first appeared in Operation: R.O.B.B.E.R.S. and made his official debut as "Fourth Grade President" in Operation: P.R.E.S.I.D.E.N.T. where Sector V escorts him to a meeting at City Hall, where he plans to shorten school days and make mandatory pizza lunches. Along the way, they are attacked by Ice Cream Men, Teen Ninjas and a robotic duplicate of Jimmy controlled by the DCFDTL.
When they get there, however, it is seemingly revealed that Jimmy was working for Father, and the changes made regarding the school day are quite the opposite of what had been planned. Since then, McGarfield began abusing his power as Fourth Grade President any way he could, until in Operation: S.N.O.W.I.N.G., he ultimately crossed the line and had to be sent to the Kids Next Door Arctic Base and Permanent Detention.
During the events of Operation: S.N.O.W.I.N.G., he plans to have Lizzie Devine, forcibly married to him and made his "queen" at a special assembly, but the first snow day of the year ends up occurring on that date, thus causing school (and the assembly) to be cancelled.In a very thinly-veiled parody of Star Wars, including Jimmy wearing a Darth Vader-like costume, Bus Walkers and Honor Roll Nerds, he attempts to capture all the kids and force them to attend the assembly. His secretary Anna, who harbors a crush on her boss, is jealous and helped Numbuh 1 rescue his captured teammates, his girlfriend, and defeat Jimmy, getting both him and herself arrested and sent to Permanent Detention.
As they board the KND S.P.R.A.Y.S.H.I.P., she reveals this to him, and says that she hopes to romantically bond with him while they are incarcerated together, which Jimmy is actually delighted by.
He is mentioned in Nigel's speech in Operation: E.L.E.C.T.I.O.N.S..
In Operation: M.E.S.S.A.G.E., it is stated that Jimmy still attends the school in Permanent Detention, despite having seemingly been taken to the KND Arctic Base. The leader of the Kindergarteners also says that he, along with his gang, had come and stolen their milk money before, revealing that Jimmy was apparently associated with the Six-Gum Gang at some point, but this is not explored further.
- Jimmy's name is a combined pun on former US presidents Jimmy Carter, Richard Nixon, William Mckinley, and James A. Garfield, and his physical appearance and accent are reminiscent of Presidents George W. Bush and Theodore Roosevelt (sans the latter's mustache).
- Jimmy was one of the few allies to turn traitor, the others being Windsor and Jerry Rassic. However, Jimmy turned traitor after a series of episodes, not just one.
- In Operation: S.N.O.W.I.N.G., he wears a black hat and coat, which is similar to Arnold Ernst Toht from Indiana Jones. He also parodies Prince Xizor and Darth Vader.
- James is one of many villains in cartoons, live-action TV and movies to use the common trope of choosing female protagonists as (usually unwilling) queens in their world domination schemes. He is the second KND villain to use this trope; the first is King Sandy.
- Jimmy's hat is white before his evil intentions are revealed, and black in the episode when he is revealed to be evil. This is a reference to old cowboy shows, where good guys would wear white hats, and bad guys would wear black hats.