What?! Are you crazy? That is a terrible, terrible idea.
~ Jasper Sitwell's last words before his death.
Jasper Sitwell is a recurring antagonist of the Marvel Cinematic Universe. He started off as a minor character in Thor and The Avengers, but later became a major antagonist in Agents of S.H.I.E.L.D and Captain America: The Winter Soldier, as he is a sleeper agent of HYDRA.
He is portrayed by actor Maximiliano Hernández.
Sitwell is introduced as one of Agent Phil Coulson's team who were sent by Nick Fury to investigate the crash landing site of Thor's hammer. He is also linked to the battle of New Mexico when Loki sends the Destroyer to kill Thor, Lady Sif and the Warriors Three. He is last seen when Coulson wishes to debrief Thor, who reluctantly joins SHIELD under the condition that they return Jane Foster's stolen items.
Some time after the Destroyer was demolished, Coulson and Sitwell met up to discuss a problem the World Security Council holds with convincing General Thunderbolt Ross to release custody of Abomination to the hands of SHIELD. Knowing Blonsky's true evil nature, Sitwell suggests to Coulson that they send Tony Stark (The Consultant) to give the point to where Ross will declare that he'll never release Blonsky. The plan was a success, much to both Coulson and Sitwell's relief.
Sitwell was sent to the Helicarrier as a computer expert. He locates Loki in Stuttgart, Germany while locating the Tesseract. His abilities are shown when the Helicarrier came under attack by Loki's hypnotized henchmen as he repairs the damage.
Agents of S.H.I.E.L.D.
Sitwell only appeared in the first season of the show, where he is assigned to work at the Hub in their mission to track down a HYDRA mastermind known as Clairvoyant, who intends to unleash the Centipede Project that involves healing his organs and unleashing an army of super-soldiers. Unknown to the other agents, Sitwell is secretly in league with John Garrett, who is revealed to be the Clairvoyant. Before Garrett's death, Sitwell was called in for a mission on the Lemurian Star.
Captain America: The Winter Soldier
Sitwell is first seen in this film on the Lemurian Star, being held captive by Georges Batroc. But it turned out that he was only there to protect secret information regarding SHIELD's Project Insight. Sitwell's true nature is revealed when he orders the STRIKE team to capture Captain America as it turns out he worked for HYDRA official Alexander Pierce. He is next shown walking with his cohort Senator Stern, who says 'Hail HYDRA' as he prepares to leave his lunch. Sitwell receives a phone call from Sam Wilson/Falcon who later on tries to get the true motives of Project Insight. He tells Captain America, Black Widow and Falcon that Project Insight's true motivations are to use a special algorithm created by Arnim Zola to target all those who posed a threat to HYDRA's plans. In the car on their way back to the Triskelion, the Winter Soldier appears out of nowhere and kills Sitwell by ramming him into the traffic, much to Black Widow's shock.