- "For I am... The Tommy!"
– Tommy Gilligan
Thomas "Tommy" Gilligan (formerly Numbuh T) is the 7 year old younger brother of Hoagie Gilligan.
He was briefly in the Kids Next Door, before removing his booger from the C.O.D.E.-M.O.D.U.L.E. in order to save the KND from Father. No longer able to join the organization, he went on to work alone under the alias "The Tommy".
In his first appearance, Operation: T.O.M.M.Y., Tommy is unable to play with his brother due to him being occupied with the Kids Next Door, and out of jealousy forms an alliance with the Common Cold to capture his brother's teammates. However, the Common Cold betrays Tommy and captures him as well. It was only through the intervention of their mother, Betty Gilligan, that the Common Cold was defeated and the operatives were freed.
In Operation: E.N.D., Tommy aids Numbuh 1 in rescuing the other Sector V operatives, including his brother, who had been wrongly decommissioned by Numbuh 86. For his help in defeating Numbuh 274, Tommy was offered a position on the KND, which he happily accepted. In Operation: T.R.A.I.N.I.N.G., Tommy and his fellow KND operatives-in-training Sonia and Lee (later Numbuh 83 and Numbuh 84) single-handedly defeated Father when he launches an ambush on the Arctic Training Base and attempts to steal the code module.
In Operation: G.R.A.D.U.A.T.E.S., he graduates from training and becomes a full-fledged KND operative, choosing the codename Numbuh T, even though "T" isn't a number.
When Father turns the entire KND organization into animals, Tommy decommissions himself in order to gain immunity to the transforming energy field, which was programmed to only affect KND operatives, and stop Father's plan. Due to failsafes in the Code module, Tommy was unable to be recommissioned, which he was fine with; opting to become "The Tommy", a vigilante devoted to protecting kids everywhere. Tommy assumes this identity in all future appearances, including Operation: S.N.O.W.I.N.G., where he doesn't wear his hat, gloves, and cape.
Tommy had a minor appearance in Operation: Z.E.R.O... He was found in Sector V Treehouse by Numbuh 3 and Numbuh 4 wanting to save the day himself, only to be transformed into a Senior Citi-Zombie by the Toilenator. While Numbuh 1 and his dad were being attacked by the zombified Hamsters, Tommy showed up still wanting to save the day only to blasted out of the treehouse along with the hamsters by Nigel. He was cured at the end of the film after Grandfather was decommissioned.
- Tommy is no longer a KND operative, but he wasn't decommissioned. This was due to fail-safes.
- The KND did try to decommission him, but gave up because he kept crying, shouting, kicking and screaming.
- "The Tommy" appears to be a parody of Batman, as his poses often resemble those seen in the 1992 Batman cartoon series.
- As his alternate persona "The Tommy", he wears a cape, gloves and fedora hat which is a parody of Disney's animated cartoon character of the same name, Darkwing Duck. Also when he says "I am The Tommy", it is a reference to Darkwing Duck's phrase "I am the terror of the knight".
- Tommy also with the cape and hat looks like The Shadow