(covers information from an alternate timeline)
Captain Thomas Halloway was commander of the USS Enterprise-D in an alternate timeline seen by Jean-Luc Picard, created when Q allowed him to prevent a fight with several Nausicaans in 2327 which led to the implantation of an artificial heart. (TNG: "Tapestry")
|Commanding officers of the starships Enterprise|
|Enterprise NX-01:||Archer • T'Pol • Tucker • Lorian|
|USS Enterprise:||April • Pike • Kirk • Decker • Spock|
|USS Enterprise-D:||Picard • Riker • Jellico • Halloway|
|ISS Enterprise NX-01:||Forrest|
|ISS Enterprise (NCC-1701):||Pike • Kirk|
|USS Enterprise (alternate reality):||Pike • Kirk|
In The Lost Era novel The Buried Age, Halloway was assigned as commander of the Enterprise even in the "proper" timeline but retired shortly before its launch, leaving Picard to accept the assignment in his stead. However, the novel also establishes that Picard's choices of Deanna Troi, Data, and Geordi La Forge for their respective positions in his crew were made based on his personal encounters with them in the months and years prior to his taking command of the Enterprise. This, in addition to his reason for choosing William T. Riker as first officer, make it highly unlikely that they would all hold identical positions on an Enterprise commanded by Halloway without Q's temporal machinations. But Q did state in "Tapestry" that nobody's history other than Picard's would be altered in any way.
Halloway reappears in the short story collection The Sky's the Limit, where it is revealed that he oversaw the construction of the Enterprise but refused to command the ship on its voyages in order to stay with his wife. A further story in the collection reveals that Halloway is killed at the battle of Wolf 359 when he commanded the USS Melbourne, having been overseeing its construction at Utopia Planitia at the time of the Borg attack.