Sean Ambrose is the main antagonist of the 2000 film Mission: Impossible II.
He is portrayed by Dougray Scott.
Ambrose was presumbly born in the UK as stated by his nationality in his IMF file and he was an IMF agent who attempts to get his hands on a new virus called Chimera, as well as its cure, Bellerophon. Ambrose has sold the virus for £37,000,000, and he intends to release the virus into the population and then sell the cure to the highest bidder. At the beginning, Ambrose was using Ethan Hunt's face while the latter was on holiday, steals the Chimera virus samples from Dr. Nekhorvich who had infected himself with a sample. Ethan Hunt is assigned a mission of recovering the virus with the help of three fellow agents (one of them being a British professional thief named Nyah Nordoff-Hall), and he manages to destroy a number of Chimera virus samples within the bio-chemical firm Biocyte Pharmaceuticals. Before Ethan can destroy the final sample, Ambrose appears and engages in a firefight with Ethan. He forces Nyah to retrieve the virus for him, but she injects herself with it before he can stop her. Ambrose kidnaps Nyah and leaves, knowing that she is now valuable to him alive, but Ethan realizes that if he does not cure Nyah with Bellerophon within the next twenty hours and left unchecked, she will die along with a number of innocent people in Sydney.
Ethan and his teammates later track Ambrose and his men during a meeting in the bunker and successfully steal the samples of Bellerophon from them. Then, Ethan's men in the helicopter locate Nyah on top of a cliff, who is about to commit suicide to prevent the Chimera virus inside her from spreading. Nyah is cured with the Bellerophon sample while Ethan and Ambrose have another firefight during a frantic motorcycle chase. The pair eventually fall onto a beach before engaging in hand-to-hand combat, with Ethan gaining the upper hand and apparently beating Ambrose to death. However, Ambrose is stil alive and laughs triumphantly as he points Ethan's own Beretta 92FS at his back. Ethan notices Ambrose's own USP Compact half buried in the sand by his feet and kicks it into the air, grabs it and spins around after tossing a Bellerophon sample to his friend Luther Stickwell. As Ambrose starts firing at him, Ethan drops to the ground before shooting Ambrose three times in the chest and back, killing him for good.