Professor Xavier and the X-Men #16

A massive Sentinel looms over the foreground of Chris Batista's cover, its imposing pink-and-purple head filling the lower half of the image as two early X-Men — Angel, wings spread wide in his yellow-and-blue uniform, and Cyclops scrambling behind him — struggle to escape its reach. Subtitled "Sentinel Rising," this February 1997 issue makes its threat abundantly clear before you've even opened the cover. At just 99 cents, Professor Xavier and the X-Men #16 delivers that classic pairing of mutant heroes and their most persistent mechanical hunters in a package that's hard to pass up.