Toril Thirteen

A Toril Thirteen was a set of thirteen warlocks who descended from the original thirteen tiefling warlocks who made pacts with Asmodeus. Some devils collected sets of these warlocks, but it was considered one of the most difficult collections to acquire because one of the warlocks, Bryseis Kakistos, had very few living heirs.

Original Thirteen
The names of some of the thirteen were unknown. The known original thirteen were:
 * Bryseis Kakistos
 * Phrenike, the most able wizard who later become a lich.
 * Caisys the Vicelord, the right-hand of Bryseis and a descendant of demons
 * Caldura Elyria
 * Titus Greybeard, the oldest warlock in age
 * Margarites
 * Pradir Ril, an Ashmadai from Durpar
 * Zeal Harper
 * Nicodemus

Known Complete Sets

 * The cambion Lorcan had a full set of thirteen warlocks by 1478 DR.

Background
In a tweet, Erin M. Evans gave a complete list of the members of the Toril Thirteen. The last four are Lahriman Jarl, Acumen Rhodion, Khorlo Sinsinger, and Nicanor, but are considered "noncanonical".