The history of comic books - specifically superhero comics - has two real starting points you can look to. We'll get to the first in due course, but the second most momentous occasion was the first issue of Fantastic Four, which saw the start of countless iconic aspects of the genre for years to come. It began Marvel's dominance of the market, and the publisher's moving away from sci-fi, horror and romance titles to focus exclusively on superheroes. It was the first big collaboration between Stan Lee and Jack Kirby, who would go on to co-create basically every big Marvel character that's still around today. More than anything, though, the first family of Marvel were the first example of what the company had to offer what its Distinguished Competition didn't. Where DC had cornered the market on superheroes for a few years before the FF debuted in 1961, it had kept its characters relatively one-dimensional and silly, as Batman and Superman descended into the Silver Age stereotype of having wacky adventures where somebody always got brainwashed, turned into a baby, or both. The Fantastic Four, meanwhile, had larger-than-life superpowers, but were totally grounded as characters. They were, and still are, a family; an unconventional one, sure, but a family nonetheless. As such, they have all the squabbles and bickering, but also the close bond that a family offers. The FF were "real" people, which made their cosmic adventures all the more relatable to readers, which has since been Marvel's standard method of character creation and the reason for their popularity.
Tom Baker is the Comics Editor at WhatCulture! He's heard all the Doctor Who jokes, but not many about Randall and Hopkirk. He also blogs at http://communibearsilostate.wordpress.com/