Avengers (1963) #257

The First Appearance of Nebula, the future member of the Guardians of the Galaxy! In the vastness of space, Captain Marvel meets Nebula for the first time, and wishes she hadn't. Meanwhile, on Earth, the Avengers follow Terminus to the Savage Land, where they are intercepted by Ka-Zar and Zabu. Plus, the creature behind Terminus' armor revealed at long last!