My Rottweiler came from his breeder with the name Spartan's Viper. I guess if you didn't know him and you saw him walking down the street you might think it was a suitable name for him. Whenever I tell people who knew him that his registered name is Viper they die laughing. He was such a softie. My boss said I should name him Adolph (boo!), and I tossed around both Jack and Gus before I landed on Levon, which I love to death and suited him to a tee. The only problem is most people pronounced it incorrectly, like "La-Vonne" instead on "Leave-On". Because of this he got the unfortunate nickname of "La-Vonne the Big Gay Rottweiler".
My Shepherd x Beagle came as Lil'Man. I was calling him Gilbert for a few days, but then I settled on Daniel, as it seemed more suited to this silent gentleman. It also went with Levon, as they are both names of Elton John songs.
My Beagle x Basset came from a puppy mill in Ohio, she was rescued and named My Little Lady, then transferred to a rescue in Ontario where they changed her name to Angel. When I adopted her I decided to keep to the Elton theme, and thus she became Little Jeanie.
My old dog wasn't really meant to be mine, but after years of dog sitting him his owners decided they couldn't keep him anymore. Because he wasn't the nicest dog it was either he stayed with me, or he got PTS. His name is Loeke (Loki) and he'll be 19 in September. I didn't even consider changing his name, I'd known him for years as Loeke.
My Saint Bernard came to me named Max, which is just a bit too common for me. I changed it to Bram, I've always liked that name. Didn't even consider another one!
My Whippet X came as Keira, a name I don't really like. I fostered her for 7 months, she ended up staying and keeping her name. I like to think I would have come up with some really neat name for her, but she's just Keira.