Wallabee in the opening credits.
Numbuh 4 disguised as Numbuh 1
Numbuh 4 in Operation: C.A.K.E.D. F.I.V.E.
If you look closer, he's smiling at Kuki!
Numbuh 4 as a Spank-Happy Vampire
Sector V scolding at Tommy for framing Chad that he did to that bike rack this morning.
Numbuh 3 and 4 are about to be run over by the Tommymobile.
Numbuh 4's level screen from "Intruders in the Park"
Numbuh 4 being mad at Bobby (ITFBTM)
Numbuh 4 booing at the Delightful Children