By now, you're probably not going to be surprised to learn that caspases come in various flavors. (Doesn't everything?)  Caspases have structural differences that reflect the differing roles they play in the apoptosis process. In particular, caspases may or  may not have associated with their  prodomain a CARD domain. This is a Caspase-Associated Death Domain that, like any other death domain, wants to get intimate with other death domains. It's very Goth.

1. Initiator caspases: Caspases 2, 8, 9 and 10. These caspases have long prodomains with CARD regions. Caspases 8 and 9 appear to be particularly important.
2. Executioners: Caspases 3, 6 and 7. These caspases have short prodomains without CARD.  Watch caspase 3. He's a troublemaker.
3. Other Caspases: also called "cytokine processors" or "inflammatory caspases." Caspases 1, 4, 5, 11, 12, 13 and 14. Long prodomains without CARD regions. Quite frankly, we won't be talking much about these caspases…because nobody else does.