cats

We have two cat, both female, and neither goes by their registered name.

One was mine from before I moved in with my partner. Her actual name is masculine and uncapitalized. But we only use that name for vet visits, and to differentiate her from our other cat. Otherwise, she is just Kitty, or "Wow," after the sound she typically makes.

The other cat we adopted together, and has a female name that is properly capitalized. We normally call her one of dozens of nicknames, though most of those are derived from her name and not just random terms of endearment.