People say you should never judge a book by its cover, but what about comic books? As comics are a more visual medium, it's hard not to be swayed somewhat by the front cover, especially on a crowded newsstand that changes on a weekly basis. Most fans may be loyal to particular titles and characters, but we're all guilty of impulse buying a random issue just because it has awesome artwork... As one of the Big Two, Marvel Comics have dominated a huge share of the market ever since they first started out as Timely Publications in 1939, and after seven decades at the top, the company is stronger than ever now that a number of successful movie adaptations have made Marvel properties some of the biggest names on the planet. To celebrate that longevity, let's take a look back at sixty of the greatest ever Marvel comic book covers. Many of these memorable images have become ingrained in the minds of fans worldwide and have become iconic pieces of art in their own right. Inevitably though, some readers will lament the absence of their own personal favorite covers, but in making this list, difficult choices had to be made. As we count down, look out for your favorite Marvel comic book covers and let us know what you think of these choices in the comments section below!