Legion of Spider-Men

Expanded upon this idea - [link]

back row, l-r;
Spider-Hulk, Silver Armour Spidey, Real Life Spider-Man ([link]), Spider-Ock, American Spider.

Mid-row, l-r;
Fantastic Five Spidey, Spider-Lizard, Ghost Spider (I think that's clever!), The Amazing Bat-Man ([link]), Spider-Thor, and Spider-Phoenix

Lower row, l-r;
Six-Armed Spidey, The Bombastic Bag-man, Spider-Ham, Black Suit Spider-Man, Ben Reilly, and Peter Parker from 'Reign'

Bottom row, l-r;
Dusk, Iron Spider, Sipder-man 2099, Zombie Spidey, Earth X Spider-Man, and Spider-Carnage.