A Constitution III-class Federation starship commanded by Captain Liam Shaw in 2401, taken off course by Picard and Riker to rescue Beverly Crusher and later renamed Enterprise-G.
The USS Titan-A was the successor to William Riker's Luna-class Titan, a refit classed as a Constitution III. In 2401 it was commanded by Captain Liam Shaw, with Seven of Nine as first officer. It is the main setting of the third season of Star Trek: Picard.
Picard and Riker board it under a pretext and Seven diverts it to the Ryton system, where Beverly Crusher and her son Jack are being hunted by Vadic's ship, the Shrike. The Titan spends the season on the run: trapped in a nebula, framed by changeling infiltrators, and finally one of the few ships free of Borg control on Frontier Day.
Shaw is killed in the last fight. A year later the ship is rechristened USS Enterprise, NCC-1701-G, under Captain Seven.