High Quality Content by WIKIPEDIA articles! Ultron is a fictional character that appears in comic books published by Marvel Comics. The character initially appeared in an unnamed cameo in Avengers #54 (1968), with a first full appearance in Avengers #55 (1968). Ultron was created by writer Roy Thomas and artist John Buscema. In 2009, Ultron was ranked as IGN`s 23rd Greatest Comic Book Villain of All Time.