Crispin (The Time of Angels)

Cleric Crispin was a cleric soldier who helped with the investigation of the crash at the Byzantium. (DW: The Time of Angels). He was later left to help protect Amy Pond along with three other clerics. He was sent to investigate the mysterious light along with another cleric, but was absorbed the Time Field crack and was forgotten along with his companions. (DW: Flesh and Stone)

Before Rory Williams was erased by a time field, Amy remembered that she could still remember the clerics, even though they could not remember each other. (DW: Cold Blood)