Olly ranks 1926 in the pet registry with 52 male animals. It's the British English spelling of the Oliver diminutive — where Americans typically write Ollie, British and Australian convention favors Olly. On a pet, the y-ending reads as warm and bouncy, and the name carries the Oliver root's charming Dickensian associations without the full formal name.
The Oliver Root
Oliver has been the top boys' name in England for a decade and is rising steadily in American usage. Olly as its diminutive inherits all of that warmth — the Dickens character, the olive branch symbolism, the general feeling of a name that has been loved for a very long time — in a more playful, casual form. On an energetic, cheerful male dog, Olly is almost perfect. Cocker Spaniels and Cavalier King Charles Spaniels carry the name's British warmth naturally.
The British vs. American Spelling
Olly vs. Ollie is a minor but real distinction. The y-ending is the British form; the ie-ending is the American. For American owners, Olly signals either British cultural affinity or a deliberate preference for the less common spelling. Ollie is separately established in the pet registry at higher rank.
The Counter-Reading: The Spelling Correction
American vets and groomers will reliably write Ollie, not Olly. Most owners who prefer the y-spelling have a standard correction ready. Oliver is in the top 10 in SSA human records; browse Oliver-family pet names for the full register.