Gaston is a French name with Germanic roots meaning something like "guest" or "stranger" — but for most English-speaking pet owners, Gaston means exactly one thing: the vain, chest-puffing villain from Disney's Beauty and the Beast. Naming a male dog Gaston is almost always a pop culture wink, and it works better the more physically imposing the dog is.
The Disney Villain Angle
Gaston from Beauty and the Beast is enormous, confident, and utterly self-delighted — which describes a surprisingly large number of dogs accurately. The name has that self-aware humor that dog owners deploy when the animal's personality has already revealed itself. "No one's slick as Gaston, no one's quick as Gaston" works as a theme song for any large, slightly show-offy male dog.
Breed Fit
Gaston lands best on large, muscular breeds: Rottweilers, Mastiffs, Great Pyrenees. On a small dog, it reads as ironic rather than matching, which is its own valid approach but changes the name's register. The human name Gaston has genuine French usage history beyond the cartoon.
The Counter-Reading: Villain Associations Linger
Gaston is charming but not exactly flattering as a character comparison. Some owners find the villain framing funny; others realize partway through the dog's life that they're constantly explaining the joke to people who don't get it. The name commits to a bit.