The X-Men #6 comic book from Marvel Comics in 1964 features an appearance by the Sub-Mariner. This key issue, graded 7.0 Fine/Very Fine by Certified Guaranty Company (CGC), is a part of the Silver Age era of US Comics. With artwork by Jack Kirby and written by Stan Lee, this single issue showcases the X-Men superhero team in a superhero genre setting within the Marvel Universe. It is a sought-after collectible for comic book enthusiasts and fans of the X-Men series.