Hyenas are an apex predator, meaning they are not preyed upon by any other animal. They are ferocious and highly skilled hunters.
Occasionally, another apex predator—such as a lion—will kill them while battling for food.
Once a hyena dies, such as through natural causes, vultures will feed on them—so technically, vultures eat hyenas.
Also note that hyenas are occasionally shot and killed by humans, but of course, don’t eat them.