~ Sir Lancelot introducing himself to Larry and his friends.
Sir Lancelot is the main antagonist of the 2014 film Night at the Museum: Secret of the Tomb, the final installment in the Night at the Museum trilogy.
He was portrayed by Dan Stevens, who also played David Collins in The Guest, David Haller in Legion, the Beast in the live-action adaptation of Beauty and the Beast, and Hal in The Call of the Wild.
In real life history, Sir Lancelot was one of King Arthur's Knights of the Round Table. He was considered to be one of Arthur's greatest knights. His affair with Arthur's wife and queen, Guinevere, had corrupted him into being vain and arrogant.
Larry and the others were saved by Lancelot when he stopped a triceratops skeleton from attacking them. He then helps them defeat a multi-headed snake and Larry tells him that they got to the Egyptian exhibit and must be on their way. When they get back, Lancelot reveals his true motives to steal the tablet of Ahkmenrah so he can win Guinevere over and this leads to a wild goose chase with Larry and the other exhibits chasing Lancelot throughout London.
He enters a movie theater playing a stage show of Camelot where he mistakes actor Hugh Jackman (Huge Ackman as he pronounces it) as King Arthur and actress Alice Eve as Guinevere, but they later correct him that it is a stage show, which gets Lancelot upset as he dashes with the corroding tablet in hand.
All of the exhibits start to turn back into lifeless statues and Lancelot's nose starts melting, due to being made out of wax. After seeing Larry and the dying exhibits mourn Dexter the monkey's death, Lancelot has a change in heart (thinking that the monkey was the task) and aligns the tablet pieces which causes the tablet to turn gold and revive everybody including Dexter.
Years later, he joins the other imported British exhibits to the Museum of Natural History in a dance party dancing next to the Easter Island Head.
He is somewhat comedic and brave, though in reality he is cruel, cunning, and deceitful as a result of his rejection and humiliation from Guinevere and wanted to steal the tablet of Ahkmenrah so he can impress her. Later, he is remorseful for his actions.