Dermot Cusack

Dermot Leon Cusack was a yeoman in Starfleet in the 23rd century, attached to Captain Christopher Pike. He had a reputation as something of a rogue.

Cusack was first attached to Pike during their days on the USS Yorktown, and went with him to the USS Enterprise in 2251. He was subsequently killed in action on Rigel VII in 2254, and replaced by J. Mia Colt.

Inconsistencies
In Early Voyages, Pike's unnamed previous yeoman from "The Cage" was named "Dermot Cusack," but in Where Sea Meets Sky, Pike references him as "Leon." Early Voyages establishes that Cusack joined Pike from his previous command, but it is Vulcan's Glory that gives a name to this command.