Howard Stark's butler, lent to Peggy Carter for one mission and unable to give her back.
Edwin Jarvis was charged with treason during the war for forging his superior officer’s signature to save the woman who would become his wife, Ana. Howard Stark got him out of it, and Jarvis became his butler. James D’Arcy plays him in Agent Carter, where Howard offers him to Peggy as support for her mission to clear Stark’s name, and where the show’s makers called their relationship the centre of the series: comic relief, in Hayley Atwell’s words, and something like Mulder and Scully in the early years, in the producer Tara Butters’s.
He came to enjoy the missions and chose to keep helping Peggy with ones that had nothing to do with Stark, such as the fight against Whitney Frost. Ana got involved too, until Frost seriously injured her, and Jarvis, in retaliation, tried and failed to murder Frost.
D’Arcy reprised the role in Avengers: Endgame, and Wikipedia’s page for the film notes that this was the first time a character introduced in an MCU television series appeared in an MCU film.
Show detailsThe two Jarvises
In the comics Jarvis is the Stark family’s butler. The films adapted him first as an artificial intelligence, J.A.R.V.I.S., voiced by Paul Bettany, and the tie-in comic Iron Man 2: Public Identity explained that the human butler did exist in this world, as a mentor to a young Tony who eventually inspired the AI. The Jarvis of Agent Carter is that man, younger, working for Howard before Tony is born. D’Arcy did not study Bettany’s performance, and is set to play the human form of J.A.R.V.I.S. in VisionQuest, which is not yet released. The AI has its own entry here.