Green Lantern #59 (1968)

This iconic comic, Green Lantern #59, is a must-have addition to any serious collector's library. Not only is it the first appearance of Guy Gardner as a Green Lantern, but it also features stunning artwork by Gil Kane and a gripping script by John Broome. The story follows Hal Jordan, the Green Lantern of Space Sector 2814, as he learns of an alternate timeline where Guy Gardner becomes a Green Lantern and proves himself to be a worthy champion. Throughout the book, readers are treated to cameo appearances by some of the most beloved characters, including Black Hand, Shark, Sonar, Dr. Polaris, and Sinestro. If you're looking for a comic that'll transport you to another universe and leave you wanting more, be sure to check out Green Lantern #59.