The Purifier is a rank in the Necromonger Empire. The role of the Purifier is to convert humans into necromongers to "replenish the ranks". It is considered to be a high rank; Dame Vaako suggests that The Purifier would be second-in-command after the Lord Marshal. This page holds the details for the character, in which he served as the (former) quatrenary antagonist in the movie.
A member of the Necromonger fleet, The Purifier revealed he was a Furyan like Riddick, and was converted. When Riddick falls unconscious after using the "Wrath of the Furyans", the Purifier pulls him into the safety of the hangar and tells Riddick how "We all began as something else". Regretting what he has done under the Necromonger influence, the Purifier said that "The Necromonger in [him]" warned Riddick not to face Lord Marshall, but that "The Furyan in [him] hopes he won't listen". Having said this, he committed suicide by walking into the sunlight of Crematoria.