Abigail "Abby" Lincoln

Numbuh 5 is the intelligent, laid-back, cool, calm, responsible, book smart and streetwise agent of Sector V, and the only one with true common sense. Like Nigel, she is one of the only members of her team that takes her missions seriously. To go along with her cool personality, she refers to herself as "Numbuh 5" in third person, saying "Numbuh 5" rather than "I" most of the time. Not only is she the smartest of her team, but one of the smartest students at Gallagher Elementary School, where she is a honor student. She is more rational, as demonstrated in Operation: O.U.T.B.R.E.A.K., where she did not jump to the conclusion that Numbuh 4 had cooties. She knew he was having an allergic reaction, and she does not think cooties are real.

Whilst arguably not as skilled a fighter as Numbuh's 1 and 4, Numbuh 5 is still a fearsome opponent, she is also far savvier in combat than the latter, often using a great level of ingenuity to defeat her opponents.

Unlike her teammate Numbuh 3, Numbuh 5 is very tomboyish, not having much interest in anything girly, such as Rainbow Monkeys, and is often seen in tuxedos rather than dresses (Although in Operation: L.I.Z.Z.I.E., Numbuh 4 complains about her "stupid girl magazines"). However, like Numbuh 3, she is considered rather attractive, as shown in Operation: R.O.B.B.E.R.S., when a member of the Six-Gum Gang tries to flirt with her, but fails since Numbuh 5 has little interest in boys. However, in Operation: M.A.U.R.I.C.E., she is shown to have a crush on Numbuh 9 ever since she was younger and was the only one to have knowledge that Numbuh 9 wasn't decommissioned.

Like her teammates, Numbuh 5 distrusts teenagers and adults, having a fierce rivalry with her sister, Cree Lincoln, who taught her most of her skills. In Operation: M.A.U.R.I.C.E., she expressed her anger of becoming a teenager to a point where she yelled at Numbuh 3 when she questions her about her birthday.