Tigers are at the top of the food chain and have no dedicated natural predators; however, some large animals do pose a threat to tigers, such as buffalo, elephants and bears. Humans are the most dangerous threat for tigers.
Large mammals sometimes attack tigers, especially when the tigers are attacking their young for food or when the tiger enters their territory unwanted. However, these animals do not actively hunt tigers to kill them, so they are not predators in the strictest sense.
Humans, on the other hand, are a legitimate threat to tigers and can be considered predators in some cases. Humans are both a passive and active threat against all species of tigers. As a passive threat, humans reduce the habitat of tigers, which in turn reduces the amount of prey available. Humans also hunt some of the same animals tigers prey on, which limits how much tigers have available to eat.
As an active threat, humans actively hunt and kill tigers. There are a few reasons for this. Some farmers attack and kill tigers to protect livestock. More often, poachers kill tigers for profit. Some humans hunt for trophies, such as the sought-after furs of tigers, while others hunt the animals to use body parts for traditional medicines in China.