Comic books have captured the imagination of children and adults alike for nearly a century. And naturally, comic book collecting is a hobby as old as the passion that fueled it.

While many different issues are sought-after by collectors, a small bunch of them are considered the holy grail of comics—rare comic books that are hard to find, wildly beloved, and expensive. Very, very expensive.

Comic books deemed exceptionally rare—for their limited run, antiquity, or content—that carry a high-ranking quality certification by the Certified Guarantee Company (CGC) have immense value. A “millions of dollars” type of value, in some cases.