In conclusion, I believe that Antioch Peverell created the Killing Curse, Cadmus Peverell created the Crusiatus Curse and Ignotus Peverell created the Imperius Curse.

This is, however, just a theory so i wouldn't put all my eggs in one basket if I were you, it could very easily been some other unknown witch or wizard how made them but who know? 

Just a quick note before I sign off; If you would like even more proof of for this theory then here it is:

If you possess all three of the Deathly Hallows you are supposedly the 'master of death' however there are more ways that one to become the master of death that is to overcome all three unforgivable curses which you may think is impossible but it's not, it's simply a very rare achievement. There is only one person in history who not only possessed all three Deahly Hallows at one point but has also overcome all three unforgivable curses; Harry Potter.

If you still are not convinced, here is the last piece of evidence I can offer: even the names match up with the curses; Avada Kedavera - Antioch - AA, Crusio - Candmus - CC and Imperius - Ignotus - II. To prove this evidence even more you could even go as far as to say that the 'fourth unforgivable curse'; Sectumsempra matches up with it's creators name; Severus Snape - SS.