Superboy #89 (1961)

In one of the most iconic Superboy comics of all time, we witness Superboy's Big Brother! This fascinating comic, originally written by Robert Bernstein in 1961, tells the story of Superboy mistaking Mon-el for his long-lost brother from Krypton. However, as the tale unfolds, Superboy soon realizes that Mon-el might not be who he seems. In a desperate attempt to test Mon-el's authenticity, Superboy paints large balls of lead green in order to simulate kryptonite. Unfortunately, the lead turns out to be incredibly toxic to Mon-el, and he finally reveals that he is actually a Daxamite who visited Krypton before it exploded.

Superboy then teams up with Mon-el to find a cure for his lead poisoning and finally decides to leave Mon-el in the Phantom Zone until he receives the cure. This exciting comic is replete with twists and turns, and it showcases Superboy's cleverness and ingenuity as he tries to uncover the truth about Mon-el.

In short, Superboy #89 is a must-read classic for any comic book enthusiast. Not only does it offer an entertaining plot, but it also introduces readers to a thrilling cast of characters. So, if you're looking for a great comic book to add to your collection, don't miss out on Superboy #89!