Valentine was a male Betelgeusian that lived in the mid-23rd century.
Valentine was aboard the USS Hiawatha in 2256 during the Federation-Klingon War, when the Hiawatha was believed destroyed en route to Starbase 36. The ship actually crash landed on an interstellar asteroid, where Valentine was among the crew and patients too injured to evacuate in the escape pods. Instead, Commander Jett Reno stayed behind to tend to the wounded, including hooking up Valentine's heart to that of a dead Bolian to keep him alive for more than ten months, until rescued by the USS Discovery in 2257. (DIS: "Brother")
Valentine was played by an unknown actor.
Given Valentine's visible heart condition, "Valentine" was likely a nickname given by Reno.
Despite Valentine clearly using the same make-up as Betelgeusians Cosmo and Yor in DIS Season 3, StarTrek.com mistakenly refers to him as a Lurian.[1]