AVENGERS (1963) #52

Black Panther breaks into the Avengers Mansion only to find the entire team decimated. And what does S.H.I.E.L.D agent Jasper Sitwell want with the Panther? 1st appearance of the Grim Reaper and of the Black Panther being an Avenger. The Grim Reaper attacks the Avengers, leaving Hawkeye, Wasp and Hank Pym for dead. It’s up to the Black Panther to save the Avengers and find the Grim Reaper to bring him to justice. The Black Panther saves the day and is offered membership on the team, which he gladly accepts.