Tales of Suspense Vol.1 #49
The Angel is affected by an atomic test done at one of Stark's weapons plants. His personality is altered and now he wants to join the Evil Mutants; The X-Men call the Avengers for help but only Iron Man is available.
Printed: Jan 1964
Writers: Stan Lee and Larry Lieber
Art: Steve Ditko, Paul Reinman, Larry Lieber, and George Roussos [as G.Bell]
Cover: Jack Kirby and Steve Ditko