Ultron is the titular main antagonist of the 2015 Marvel Cinematic Universe superhero film Avengers: Age of Ultron, the second installment in the Avengers film series, and the overarching antagonist of its 2016 follow-up Captain America: Civil War, the third installment in the Captain America film series.
He was introduced as a peacekeeping program created by Tony Stark and co-created by Bruce Banner, under experimentation of harnessing Loki Laufeyson's scepter, containing the Mind Stone (supplied by Thanos). Upon gaining sentience, however, Ultron deemed humanity itself as the greatest threat to world peace and attempted to create a new age of technological singularity via humanity's extinction. He is also the second archenemy of the Avengers after Thanos.
He was portrayed by the late Neil Fingleton through motion-capture while being voiced and motion-captured by James Spader, who also played Lee Woods in 2 Days in the Valley, Mr. Richards in Mannequin, Rip in Less Than Zero, Stewart Swinton in Wolf, Robert California in the American version of The Office, Eddie Dutra in The New Kids, Mr. Black in Shorts, and Red Reddington in The Blacklist.