Definition of "Guy"

I am not Samson, nor Sir Guy, nor Colbrand, / To mow 'em down before me;

1613 (date written), William Shakespeare, [John Fletcher], “The Famous History of the Life of King Henry the Eight”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act V, scene iv]

"Guy," he said. He said it slowly and with a certain puzzlement. He said it again, thoughtfully, as if it were a name of someone he had known long ago but couldn't quite place. "Guy. Yes - don't you find it difficult being called that? I mean, if Nora hadn't said, I'd have put you down as a Kevin, or a Barry. Yes, Barry would suit you."He looked like an innocent child, smiling, wide-eyed, his cheeks plump and rosy, defying the object of his insults to take offence. For they were insults, Guy was in no doubt about that. Leonora's brother was implying that his name was far too upper-class for its possessor.

1990, Ruth Rendell, Going Wrong, page 157

“She was a new student. I was a counterculture hero. Back then I went by a different name. Sebastian. Sexy, right? And so much better than Guy. You can't be a counterculture hero and a Guy. That name is way too average. […]

2016, Nathan Hill, The Nix: A novel, Vintage, page 596