I will preface this by saying I know that my 'requirements' are a little odd, I would consider it some kind of OCD, but I wouldn't want to undermine anyone with OCD.
Over my life time I have had a lot of pets, it has become some kind of family goal, that by the end of our lives we will have had a pet for every letter of the alphabet.
The letters we have left are A, E, F, Q, U, V, X.
My dogs (past and present) initials currently spell out BOW so a letter that extends this to another word like BOWS would be acceptable despite breaking the alphabet rule.
Or, our dog's name is a Disney main character, so another Disney main character would be OK, or another Tom Hanks character.
I have googled and not come up with an awful lot other than Sully. I would appreciate any input or creativity as I am drawing a blank.