Ensign Walsh was a 22nd century Earth Starfleet engineer who served aboard the NX-class starship Enterprise NX-01 under Captain Jonathan Archer.
In March 2153, he was working in the situation room on the bridge when Enterprise rescued Captain Archer and disabled a Klingon starship. (ENT: "Bounty")
Walsh would later remain aboard Enterprise during the vessel's search for the Xindi weapon throughout that year.
He was working in the command center on the bridge when the bridge section was enclosed in a bunch of spatial anomalies and the atmosphere began to fill with ammonium sulfide. (ENT: "Harbinger")
In an alternate version of 1944, Walsh assisted Commander Trip Tucker to repair one of the starship's shuttlepods, which had been damaged in an attack by a squadron of P-51 Mustangs. In order to repair the craft, the shuttlepod required a new EPS conduit. Tucker asked Walsh to retrieve a replacement conduit from the injector assembly in engineering. (ENT: "Storm Front")
In 2155, he had a meal in the mess hall. (ENT: "Terra Prime")
