Grainger made his Marvel Comics debut inking a backup story in X-Men #55 (April 1969), over penciler Werner Roth. He went on to ink further X-Men backups as well as covers and interior stories in The Avengers (over John Buscema, Sal Buscema, and Gene Colan); the satirical comic Not Brand Echh; The Incredible Hulk and Nick Fury, Agent of S.H.I.E.L.D. (both over Herb Trimpe); and the feature "Ka-Zar" in Astonishing Tales, over industry legend Jack Kirby.
