Valentine 1

Valentine "Val" McGillycuddy was an American surgeon and humanitarian who was controversial in his time for building peaceful relations with the Lakota people. He reportedly was a close friend of chief Crazy Horse. His urn at the top of a mountain in south Dakota says "Holy White Man" in Lakota.

Valentine Morgenstern is one of the major villains in Cassandra Clare's "The Mortal Instruments" series.

Valentine Morgenstern from Shadowhunters. End of story.

I'm surprised no one has mentioned it yet... but there was a character in Fallout Four named Nick Valentine (not a toaster) who helps you find your son, Shawn. He's a synth and has his own detective agency in the heart of Diamond City. Valentine can be set as a companion (and he's just pretty cool. A synth as a companion //SPOILER WARNING x"D//
SERIOUSLY, SMALL SPOILER --
Who is actually a cop from 2077 with his memories put into a robot to stay alive as an experiment? So sad but so cool).

Valentine Michael Smith is the full name of the main character in Robert Heinlein's novel "Stranger in a Strange Land."

In the film "By Hook or by Crook," Valentine is the main character, a female to male transvestite.

Valentine is also the name of Maximillian Morrel's lover in "The Count of Monte Christo".

In the movie Mirrormask, one of the main characters was named Valentine.

It's the name of Ender Wiggin's sister from the book Ender's Game by Orson Scott Card. I think it's better for a girl than a guy.