Billy is an unseen human character in the original Nintendogs game. He owns a golden Dachshund named Aster.
Billy is very friendly, but his pet Aster isn't. He often gives out advice, no matter what trainer point level you are at. Sometimes, when he's not giving out advice, his dog can be seen at the park, or he has entered it into a contest.
- His dachshund Aster does not appear in Nintendogs + Cats, but a Dachshund named Loulou (Trixie in the PAL version) owned by Joe does, and has the same personality as Aster, and also has a similar appearance.
- It is unknown if Billy is a boy or actually a girl, due to the fact that his name is also used for girls, too.
"What a fit (dog breed)! I bet that could easily take first place in a contest!" -When he has time to talk.
"Did you just leave that pile of poop behind?" -When you neglect to clean your dog's poop up.
"Agility trials are the hardest. If you want to become a champion, then you must go to the gym found on walks." -Giving out advice on Agility trials.
"Has this dog ever won any (contest name)? Was it in (class)? I was in that contest, too!" -Commenting about a dog's performance in a contest.