|Sector V (former)|
|Family||Mom, Numbuh 2, Grandma|
|Friends||Sector V, Sonya, Lee|
|Enemies||Villains, Father, The Delightful Children From Down The Lane|
|Nicknames||Tommy (called so by everyone), Numbuh T (called so by himself, and a few other members)|
|Voiced by||Dee Bradley Baker|
"For I am...The Tommy!"
Thomas "Tommy" Gilligan is the 7 year old younger brother of Hoagie Gilligan (Numbuh 2).
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 Sonya 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.
This storyline is concluded in Operation: G.R.A.D.U.A.T.E.S., in which he graduates from training and becomes a full-fledged KND operative, choosing the non-numerical codename of "Numbuh T".
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, except Operation: S.N.O.W.I.N.G., where he doesn't wear his hat, gloves, and cape.