Who first appeared in Rom #1 by Bill Mantlo and Sal Buscema, which hit the stands on September 4, 1979.
Captain Marvel, who would go on to lead my favorite superhero team ever (no, not The Avengers, NEXTwave!), first appeared in Amazing Spider-Man Annual #16, by Roger Stern and John Romita, Jr.–maybe the greatest writer/artist team in history.
The book went on sale August 31, 1982. And the story title? “Who’s That Lady?” Clearly a tribute to the Isley Brothers.
At the time, I believe Monica Rambeau was the third person to use the name Captain Marvel–after Mar-Vell and Rick Jones.