The company existed (as Timely Comics and then Atlas) from the 40s, but it was Stan who turned it into Marvel with FANTASTIC FOUR #1. As Stan tells the story, publisher Martin Goodman had played a game of golf with DC publisher Jack Liebowitz and Liebowitz was boasting about how the new JUSTICE LEAGUE OF AMERICA book was selling. Goodman instructed Stan to come up with a team of super-heroes and the result was the FF. The rest is (Marvel) history.
Marvel Comics has benn around since the late 1940's.
Back then it was Timely Publications and before the risde of super-heroes, was monster, romance, and other stories in comic form. Timey was run by Martin Goodman, and had writers and artists like Jack Kirby, Joe Simon, Bill Everett, and later Stan Lee.
Stan became the editor pretty quick due to him being the only one willing to do it.
Back then they were putting out characters like Captain America, the Human Torch, the Sub-mariner, and countless other titles that didn't survive the 50's. In the late 40's, early 50's super-hero comics stopped selling, so Timey, now named Atlas, published Westerns, Mosters, and other odd titles.
In 1961 Stan Lee, on the verge of quitting, was asked by Goodman to make a superhero team like DC's the Justice League. Not wanting to write kiddie fluff, Stan chose to write it the way he wanted to, figuring he had nothing to lose. He, along with Jack Kirby created the Fantastic Four.
Goodman hated it, but published it anyways. When FF sold well, Goodman was pleased and asked Stan to create more.
Stan got with Steve Ditko to create Spider-man. Goodman hated the idea of Spider-man being a teenager (teen's were supposed to be sidekicks to him) and that he was a kid with problems. He published it, and it sold big. This became a theme for many of Marvels early books and continues today. Super-heroes that have problems in real life and that are set in real cities (in contrast to Superman who's only hangup back then was trying to avoid being discoved that Superman and Clark Kent were the same, by Lois Lane).
After Spider-man several new books popped up. Thor, Iron Man, the Hulk, as well as Ant-man/Giant-man and Wasp. Marvel eventually decided to bring those characters together in the Avengers. Few issues into the book, bring the return of Captain America. The same year the Avengers debuted, saw a minor title called the X-Men come out. More new books came out afterwards. Doctor Strange, Daredevil, and others. Marvel was doing good throughout the late 60's and early 70's. In the early 70's Marvel decided that X-Men wasn't selling well enough to bother publishing new stories, so they printed reprints of previous issues.
In 1975 Marvel discovered that interest in X-Men was growing, so they decided to basicly do as the Avengers had done, replaced the old with new. Four of the original characters were replaced by five new ones, and two former guest stars.
These new X-Men created by Len Wein and Dave Cockram caught on quick. Wein left the book a few issues later to the man who would make the X-Men the icons they are today, Chris Claremont.
In the 80's Marvel really started to peak. They came out with the first of many X-Men spin-offs in New Mutants. That led to more X-Men spin-offs as well as an Avengers one in West Coast Avengers.
Many popular artists and writers debuted back then. John Romita Jr., son of the legedary "Jazzy" John Romita, Loiuse Simonson, Walter Simonson, Frank Miller, Rob Liefeld, Marc Silvestri, Jim Valentino, Eric Larsen, Jim Lee, Peter David, Todd Macfarlane....among others.
In the 90's saw Marvel's downfall, and the peak and bust of the comics bubble. It started with several hot writers and artists, who were creating very hot characters and had spin-offs created for them. Jim Lee had X-men, Rob Liefeld had X-Force, Todd Macfarlane had Spider-Man, and Marc Silvestri was working on Uncanny X-Men. Marvel decided to take advantage of the Direct Market (Comic Book Shops) by publishing multiple versions of the cover for Spider-man #1. Fans, and the dreaded speculators (people who buy stuff cheap expecting to make 5-10 times their money) bought them all. Stores were given rarer copies if they ordered a certain amount. Marvel copied this with X-Men #1, which had five different versions. Marvel started to pump out and endless stream of spin-offs, and started making certain groups their own "universes". They made covers with Holograms, Foil, Glow in the dark, and others which were concidered collectors items.
Marvel also had many artists/writers quit to form their own company. MacFarlane, Leifeld, Valentino, Larsen, Jim Lee, and Marc Silvestri founded Image, where they could make money off their own creations. Other companies sprang up to compete with Marvel and DC. Valiant, Chaos, Malibu....all offering multiple enhanced covers. Marvel decided to become more independant. They started buying up companies like Fleer and Skybox(makers of sports cards), Panini (an Italian Sticker company) Malibu comics, and Heroes World Publishing, and merged with the toy maker Toybiz to create the public traded company Marvel Inc..
With Heroes World, Marvel decided to bypass distributors like Diamond Distibution, and self distribute. This caused Diamonds competition to go under. In the Mid 90's the bubble burst with the DC's Death of Superman. The event caused wide spread demand. The only problem was that DC printed enough copies to meet the actual demand. People took their copies then a week later sold them back to the store for like 25-30$ a piece. The store then upped the privce to $50-60. Eventually people stopped buying the high priced copies. Stores were stuck with 20-30 copies of all these "collectors edition" books, and they weren't selling.
The backlash to DC wasn't much since they were backed by the conglomerate Warner Bros. Marvel however was affected. Their stock, which went as high as $25 a share plumetted to mere cents. Heroes World went bankrupt. 50-75% of Marvels books were canceled. The company was on the verge of a hostile takeover and was deeply in debt. Marvel finally declared backrupcy and filed for chapter 11 Bankrupcy protection.
Marvel was eventually reorganized under the control of Toybiz. Renaming itself Marvel Enterprises, renegotiated a deal for the rights to Spider-Man the movie. In 1998 Marvel had it's big break with the movie Blade. The first successful movie made of a Marvel Character. In '99 X-Men came out, breaking records and setting the stage for Marvels return. While the Spider-Man movie was being made, the comic itself was a wreck.
In the late 90's the comics decided to bring back a character from 1975, Peter Parkers clone, calling himself Ben Reily. Marvel kept going with this "Clone Saga" by revealing that the clone was actually the real Peter Parker. Basicly Marvel was saying to it's fans that thse past 20 years you've been reading about the character, was wrong. Fans were very, VERY vocal about their displeasure. Marvel eventually choose to right their wrong and kill off Ben and say that Peter was the real one. Marvel kept trying to fix the mess, but instead kept screwing it up.
Eventually Marvel got the writer of the TV series Babylon 5 , J. Michael Strazynski to write the book. Marvel also managed to get former writer and artist, Joe Quesada and Jimmy Palmotti to return to Marvel from their own company, Event, to do a few books how they want. They managed to get cult favorite writer/director/producer Kevin Smith to write a story arc of Daredevil.
Daredevil was relaunched under the new imprint Marvel Knights. Along with Black Panther and Inhumans...Marvel Knights became a hugely successful line. It was so successful that Quesada was named Editor In Chief. Over the last ten years Marvel ticked off many big name writers and artists that mostly refused to work for them again. Quesada helped heal those rifts and got more big name talent to work at Marvel again, as well as new ones like Grant Morrison and Frank Quietly who were on the controversial Authority. Even the long awaited JLA/ Avengers is coming. Now many once dead books have been revived by great art and better stories. So many that after Spider-Man movie came out, Daredevil, Hulk, and a sequel to X-Men and Blade came out, each becoming blockbusters. With Punisher, a Spider-Man sequel, Blade III, Ghostrider (with Nicolas Cage) and more movies from Marvel getting made, Marvel Comics is back to being #1.