In 2252, Finnegan, a flamboyant Irish upperclassman, tormented cadet James T. Kirk in his first year at Starfleet Academy. Looking back from the perspective of years, Kirk described himself as "positively grim" during that era, a fact that delighted jokester Finnegan immensely. The sort of fellow who would put a bowl of cold soup in your bed, or leave a bucket of water propped over a half-open door, Finnegan tormented Cadet Kirk mercilessly.
In 2267, the USS Enterprise discovered the Shore Leave Planet, a place where one's fantasies were made real. On that world, Kirk encountered a version of Finnegan, exactly as he had appeared so long ago. At that point, Kirk did not understand the nature of the planet, and so he sought answers from Finnegan, who was the first character that actually interacted with the landing party. These attempts earned Kirk only japes and mockery, and finally Kirk had enough – he chased down Finnegan and "beat the tar out of him" – something he'd been longing to do for years. During their fight, Finnegan offered a valuable clue in his statements, "Kinda makes up for things, huh Jim?" and, "I'm being exactly the way you remember me." At the end of the fight, Kirk and Spock realized that Finnegan, like all the other robots, had been created in response to Kirk's unvoiced desire for revenge. (TOS: "Shore Leave")
Background information Edit
Finnegan was portrayed by actor Bruce Mars. At one point, Finnegan referred to Kirk as a plebe. Assuming this usage corresponded to modern naval usage, this would mean Kirk was a first year cadet at the time Finnegan tormented him. There was a modern US Navy tradition of upperclassmen inflicting various sorts of odious duties on plebes at the United States Naval Academy, but Finnegan's antics seem to go beyond what was currently tolerated.
Finnegan was the only significant character to wear the early 23rd century Starfleet cadet uniform. Since Finnegan was a cadet in the 2250s, we can assume this uniform Kirk remembered him wearing was from that era. Since the costume was reused, unchanged, on Starfleet extras in late-2260s episodes, it established that cadets of both eras wore the same design of uniform. (TOS: "The Trouble with Tribbles", "Wolf in the Fold")
Finnegan appeared in the comic book stories "Starfleet Academy!" (Star Trek Annual (DC) volume 2 #2), "Old Loyalties" and "Finnegan's Wake!" (DC TOS volume 1 #54-55). The latter two stories depicted him in the 2280s, as a commander serving as an investigator in the Federation Security Legion who was sent to the Enterprise to investigate the attempted murder of Kirk. Although he took the investigation seriously, Finnegan was still a prankster much to the frustration of "Jimmy" Kirk who fell in his own attempts to get even. Finnegan does acknowledge, in private, that Kirk had a genius for commanding crew loyalty.
A family member of Finnegan's made an appearance in the first of Peter David's Starfleet Academy books, remarking after playing a prank on Worf that he came from a long line of Academy pranksters before Worf taught him a lesson.
His mirror universe counterpart was mentioned in the short story "The Greater Good" contained in the anthology Shards and Shadows. While he was an upperclassman, he took great pleasure in bullying Kirk. However, with Simon Van Gelder's assistance, Kirk murdered Finnegan while still attending the Academy. Kirk later commented that "[e]ven death couldn't wipe that stupid grin" off Finnegan's face.
His alternate reality counterpart was James T. Kirk's would-be "killer" and "victim" in the titular challenge of "The Assassination Game". Kirk dodged one attempt by utilizing a variation of the corbomite maneuver, claiming that he had accidentally spilled chemicals that were going to explode if Finnegan didn't leave the room immediately. His first name is also given as "Jake".