Eel

A slippery presence from Marvel's Copper Age, Eel made their debut in The New Mutants Annual #5 in 1989, brought to life by the creative duo of Louise Simonson and Rob Liefeld. With only three catalog appearances spread across the annuals of Avengers West Coast, Fantastic Four, and The New Mutants, this is a rare, blink-and-you'll-miss-it figure — the kind of deep-cut discovery that makes digging through back-issue bins so rewarding. Eel keeps genuinely impressive company, sharing pages with icons like Captain America, the Human Torch, and fellow aquatic-themed characters Sharkskin and Undertow, making those annuals a surprisingly rich haul for collectors who love unearthing the overlooked corners of the Marvel Universe.