After looking at hundreds of comic book covers, it becomes quickly apparent that not every cover is 100% original. Whether done intentionally or even underhandedly, there's something about uncovering these "swipes" that adds a new element of fun to reading and collecting comics. Todd McFarlane's adjectiveless Spider-Man #1 was one of the best selling comics ever. It's gone on to inspire many homages and swipes over the years.
Spider-Man #1 Spider-Man #1
August 1990
Todd McFarlane
 Lethargic Comics, Weakly #3 Lethargic Comics, Weakly #3
August 1991
Greg Hyland
Spawn #8 Spawn #8
February 1993
Todd McFarlane
 Skin13 #½A Skin13 #½A
1995
Bill Maus
Marvel Zombies #1 second print Marvel Zombies #1 (2nd)
February 2006
Arthur Suydam
On Ebay: Spider-Man | Todd McFarlane | Spawn | Lethargic