Fat-tailed may refer to:
In mammalogy:
- Dwarf Fat-tailed Mouse Opossum, opossum species from South America
- Fat-tailed Dunnart, species of mouse-like marsupial of the Dasyuridae family
- Fat-tailed False Antechinus, member of the Dasyuromorphia order
- Fat-tailed Gerbil, rodent belonging to subfamily Gerbillinae
- Fat-tailed sheep, category of domestic sheep that comprise approximately 25% of world sheep population
In other fields:
- African fat-tailed gecko, nocturnal, ground-dwelling gecko
- Fat-tailed distribution, phenomenon of approximately normal probability distributions that emerge in practice