In the Poldark novels (published 1945-2002) by Winston Graham, Garrick is the name of the character Demelza's dog. See https://en.wikipedia.org/wiki/Poldark for reference.
I like this name. A nickname could be Gary or Rick, and since Gaz is a nickname for Gary, that's another one. It sounds masculine, honest, and forthright.
A famous bearer (since the Harry Potter series is so popular) is the wandmaker Garrick Ollivander.Also, there's a character in Star Trek: Deep Space Nine whose name is spelled Garak but pronounced like this name. He's an exiled Cardassian tailor and former spy (well, he switches back and forth between "former" and "current", the show has a lot of politics in it), and surprisingly one of the best developed characters in the show.
This is my husband's name and I've always loved it! It is phonetic so when people see it in writing they are always able to pronounce it. Plus it is really uncommon.On the downside, EVERYONE he meets thinks he's saying "Garrett" and there aren't any nicknames.