Breeders name a litter from one letter, some registries require it, and plenty of people want a second animal's name to match the first. The first four letters covered S, M, B and C; these are the next four by volume.
Can I filter names by any letter?
Yes. The archive's Starts with control takes any initial and combines with every other filter, so a request like female cat names starting with K is one query rather than a search through a list.
Every count on this site is a tally of real registrations: pet licences and shelter intakes published as open data by New York, Seattle, Austin, Montgomery County, Cambridge, Zurich, Basel and three Australian councils. Popularity here is the average share a name holds across those registers, so a name common in a small city is not buried by one common in a large one. Nine of the eleven sources are North American, so read the ordering as naming in those places rather than worldwide. Browse the whole catalogue or read how the data is put together.