Ensign Trancas was a Human man in Starfleet in the 23rd century. He served as a security officer aboard the USS Enterprise, under the command of Captain James T. Kirk. He was a big, burly man from a slightly high-gravity world.
In 2270, Ensign Trancas led a security team consisting of Hasmid and Kasuki assigned to search the recreational area on Deck Eight of the Enterprise for the missing Caitian officers M'Ress, M'viore and R'leez, all of whom were suffering from hormonal reactions and were acting wild. Instead, they were attacked and wounded by the Caitians. (TAS - Log 10 novelization: The Slaver Weapon)