The Dominus Pet is a pet that can be bought with Robux in Zombie Attack. You can get this by purchasing the Dominus Pet gamepass. It is a healer, attacker, knock backer, and a jump booster type of pet.
This cost 1000 ROBUX, so Robloxians would spend from $9.95 to $14.90 to get the pet if they had 0 ROBUX before.
Trivia: This pet came from a ROBLOX catalog item that cost over 6 million ROBUX. The link is https://www.roblox.com/catalog/21070012/Dominus-Empyreus