The start of the Silver Age! This year* introduces the formation of the Fantastic Four, the Hulk, Spider-Man, Ant-Man, and Thor. It's a pretty big year! There's no interaction between titles at this point, with the exception of Strange Tales's Human Torch stories and the main FF title. Even that is something of an innovation if compared to DC solo characters and their JLA appearances.

Skrulls are first introduced here (we've seen some retroactive appearances prior to this, but this is the first published appearance). The Sub-Mariner's first modern appearances occurs here. Commies were pretty much the #1 threat.

Stan Lee handles all of the writing with a little scripting help from his brother Larry Lieber. Jack Kirby and Steve Dikto handle the art.

First appearances: Mr. Fantastic, Invisible Girl, Human Torch, Thing, Mole Man, Dr. Doom, Puppet Master, Spider-Man, Aunt May, Hulk, Rick Jones, Betty Ross, General "Thunderbolt" Ross, Ringmaster, Thor, Ant-Man, Egghead

*Actually the FF's first issue was November 1961 but since it was basically Marvel's only super-hero comic for that year and since my early FF issues are all bundled in one trade, we're starting the categorization at 1962.

Fantastic Four #1-10 Formation of the FF. 1st Dr. Doom & Puppet Master. 1st Sub-Mariner in modern age. 
Tales To Astonish #27 1st Ant-Man (Henry Pym) 
Hulk #1 1st Hulk 
Amazing Adult Fantasy #14  
Strange Tales #114 (Dr. Strange)  
Hulk #2  
Journey Into Mystery #83 1st Thor in modern age 
Amazing Fantasy #15 1st Spider-Man 
Journey Into Mystery #84  
Tales to Astonish #35  
Hulk #3  
Strange Tales #101 (Human Torch)  
Strange Tales #102 (Human Torch) 1st Wizard 
Tales To Astonish #38 1st Egghead 
Strange Tales #103 (Human Torch)