Butler is an occupation name repurposed as a pet name — a choice that either leans into irony (the dog does no service whatsoever) or affectionately acknowledges what the dog actually does (fetches things, escorts guests to the door, maintains household order with quiet authority). Both readings are valid and both are in play among the 36 owners who registered this name.
The Aristocratic Household Aesthetic
Pet names drawn from servant roles (Butler, Nanny, Steward) belong to a tongue-in-cheek upper-class aesthetic that's always been present in pet naming. Butler in particular suits large, dignified male dogs who move with purpose and look at you steadily. A Great Dane or Weimaraner named Butler is barely even a joke; it's just accurate.
The Pop Culture Layer
Rhett Butler from Gone With the Wind gives the name an additional Southern Gothic layer: charismatic, slightly dangerous, ultimately uncontrollable. A male dog named Butler in a Southern household may be drawing on that specific lineage. The connection is usually understood without needing to be stated.
Sound in Daily Use
BUTT-ler has the slight disadvantage of its first syllable in a name-recall context. Most owners report this is not actually a problem in practice. The name calls cleanly and carries authority.
The Counter-Reading: The Irony Must Be Maintained
A dog named Butler who provides no services whatsoever (and most dogs do not) has owners who understand they've made an ironic statement and are fully committed to it.