Pimli Prentiss born Paul Prentiss, was the warden of Algul Siento. He was tall, overweight, and balding.
Prentiss he adopted the taheen name Pimli during his induction ceremony, after being recruited by the Crimson King to run the Devar-Toi, the Crimson King's prison for Breakers. He got the job by replying to a help wanted advertisement in a daily newspaper. Pimli did not reside in the universe in which Algul Siento existed, but a parallel Earth very similar to Keystone Earth, where he worked as a prison guard.
Pimli is shown to be cautious and restrained in his approach to his service to the Crimson King. He relies on his humanity and spirituality to guide him in his endeavors, as he is a newly devout Catholic, his faith apparently being triggered by his experiences in End-world.
Pimli was killed by Roland Deschain's ka-tet during the Battle of Algul Siento. Before dying, he was able to inflict a mortal gunshot wound on Eddie Dean, thus breaking Roland's ka-tet.