Amazing Fantasy #15 (August, 1962)

Synopsis

Here's where it all began.  I probably don't have to sum this one up, but I will.

Peter Parker is the school wallflower. When he's bitten by an irradiated spider at a "Science Exhibit" he gains the proportionate strength and speed of a spider! He becomes a masked sensation on television, and shows off his abilities. 

When his uncle Ben is killed, Peter races to the abandoned warehouse to nab the killer. It is then that he learns that his uncle's killer was the same man he chose not to stop earlier in the issue.

We close with a lesson from Stan-the-Man: With Great Power, There Must Also Come Great Responsibility.

Notes

• Flash Thompson and Liz Allen appear, but are not named
• Peter's pupils can be seen through his mask on pg. 11 
• He is referred to as Spiderman or even The Spiderman, but never Spider-Man
• The reader is directed to the "next issue" of Amazing Fantasy, but that wouldn't be published for another 33 years

Credits

Stan Lee, Steve Ditko