The mobile game Herodom, a game combining elements of tower defense and interactive combat, features over 150 unique units. Herodom's creator sanderfreken has open sourced a character spritesheet generator for the assets from Liberated Pixel Cup, which the game uses. Here's how they describe it:
"There are tons of items, clothes, weapons and armours to combine with the huge amount of available bodies. As for Herodom I needed to be able to create new characters in an easy way, I continued working on the LPC sprite sheet generator. This generator integrates all LPC character sets, and allows the user to compose his own sheet, and export it.
Once exported, you might post process the sheet to only select the image sets you want from it. By default, it contains all available LPC animations, which are: Walking, Thrusting, Slashing, Spellcasting and Dying. All animations are available in 4 directions, except for the death animation."