Such hybrids are called tions and ligers. Do they challenge the definition of species? Not really. The key words are "interbreed successfully"; tigons and ligers generally are sterile and short ...

A zebra and horse hybrid. Zorses usually have a horse's body with zebra-like stripes. A hybrid between domestic cattle and American bison (buffalo). Beefalo are bred to combine the hardiness of bison ...

Jaglion: A cross between a male jaguar and a female lion, these rare hybrids are known for their striking appearance and unique combination of features. Geep: A cross between a goat and a sheep.