Orsino is an elf and the First Enchanter of Cirlce of Magi in Kirkwall and one of two main antagonists of act 3 of Dragon Age II.
History
Despite acting a caring person, he is ready to sacrifice everything to save his own skin. He supported a serial killer Quentin by giving him access to books about forbidden magic and was hiding his existence in secret. When he and his fellow mages were threatened by Meredith Stannard's power he called nobles of Kirkwall to revolution and had no shame to ask for help people, who's relatives were slaughtered by Quentin he willingly supported.
After the apostate, Anders starts the insurrection, Orsino asks Hawke to aid the mages.
In the end of the game he eventually admits he knew about Quentin, but claims he didn't know he's a murderer. In order to slay his enemies he used Quentin's magic to turn into a living collected corpse called Harvester, but was killed in battle.