A Cape Cobra (Naja nivea) eating a Puff Adder (Bitis arietans) (source of photo unknown)
Cobras will have a preferred prey to eat but some will eat any animal they can catch.
In this photo a Cape Cobra - one of South Africa's Deadly Dozen Snakes, is eating another of South Africa's Deadly Dozen - a Puff Adder.
Cobras also eat frogs, rodents, birds, lizards and even fish.