Of heroes and pets

Im still pretty new and dont know if there is a listing of all the heroes you can get and WHERE/HOW you get them. I really need the same kind of thing for pets. I have all three guild wars games. I took my tyrian warrior to nightfall to get heroes and so far I have Tahikora, Koss, Dunkoro, Melonni, and Acolyte Jin. where can I get a necro hero? Also, outside the Astrilarium, there is a Green drake but I cant seem to get it for my heroes pet, is there a trick to it?

I would suggest http://gw.gamewikis.org - you can search for just about any game information you want.

Thank you. That was exactly the information that I needed.