Otters
British wildlife officials are concerned that river otters are showing signs of cannibalism and infanticide. This has not been the modus operandi of the otters in the past, and researchers worry that negative environmental factors have threatened the sanity of the population.
More: Fears grow for otters' sanity

Hippos
The mass-deaths of herbivore hippo pods in Uganda due to anthrax may have been made more lethal due to some unusual cannibalism instances. The theory is hippos, stressed from overcrowding, have taken to eating meat, including impala and other hippos that have died of anthrax.
More: Hippo Cannibalism Spreads Anthrax

Sea Lions
Instances of cannibalistic behavior often seem to occur in very stressed populations. The sea lions of New Zealand are an endangered species and researchers don't know why adult males are targeting seal pups, but it is of grave concern.
More: New Zealand Sea Lions Cannibalism

Tigers
Captive animals often exhibit odd behavior, and tigers are no exception. Zoo tigers have been known to eat their young, although the reasons are unclear.
More: Tiger Cubs

Ants
Ants colonies will often fight amongst themselves. When a rival ant queen is killed, the queens of some species will eat the queen, eggs and larvae. This allows the surviving queen the nutrients she needs to produce more baby ants and keep her colony strong.
More: Foraging, Fighting and Queen Behavior

Butteryflies
Species like butterflies go through a metamorphosis. At different stages, they are known to prey upon their own species. Monarch caterpillars will eat Monarch Butterfly eggs as part of its constant munching before it cocoons itself and becomes a butterfly.
More: Amherst: Thomas Oliver Thesis

Rabbits
Despite herbivore status, rabbits have been known to eat their young. It occurs most often with stressed new mothers. Disruption of the nest, loud noises, unusual smells, visits from pets, an unbalanced diet and lack of water can lead to this kind of behavior.
More: Rabbit Cannibalism

Japanese Macaque
A recent study found that at least five primate species, including Japanese Macaque, baboon, chimp and gorilla, engage in cannibalism. However, its unclear if this is truly cannibalism or mostly infanticide as only in some cases are the young consumed.
More: Cannibalism in Nonhuman Animals

Birds
Crows and ravens have been known to target the eggs and young of rivals in order to make it more likely they will breed successfully. Several gull species which live in large nesting colonies, where competition for food is fierce, will regularly prey upon chicks and eggs.
More: Animal Bytes: Gulls

Vultures
Some bird parents, like the Bearded Vulture, have worked cannibalism to their advantage to feed their young. They hatch two eggs, about a week apart, and the stronger chick then brow-beats the younger sibling until it starves to death. Then it becomes big brother's next meal.
More: Eating Among Friends

Lions
Lions engage in cannibalism for a number of reasons from starvation and to new dominant males taking over a pride. In this case, he kills off the newborn cubs in order father his own cubs and pass on his own, stronger genes, instead. When he eats the cub, it would be classified as cannibalism, however if he just kills it, it's considered infanticide.
More: Diversity in predators

Grizzly Bears
With grizzlies, it's the cubs that have to watch out. When a grizzly male wins mating rights with a female with cubs, he may, on occassion, kill off her cubs, thus forcing the female to be able to breed with him sooner. This is one of the key factors in cub mortality.
More: Infanticide in grizzly bears and Kodiak Bear Fact Sheet

Sandtiger Sharks
Sandtiger sharks get a little snacking in before they are even born. The fetus feeds on the yolk sac and eggs. As baby sharks develop little teeth, they eat other, smaller siblings, ensuring it is the strongest young survive to birth. This is a process called intrauterine cannibalism.
More: Aplacental viviparity

Polar Bears
When you live in a barren environment on ice, you need to take your meals as they come. With global warming, the bears have to trek farther in order to catch seals, and sometimes, they look to their own for survival.
More: Cannibalism of Yearling Polar Bear

Komodo Dragons
An opportunistic meat-eater, the Komodo Dragon needs to eat but relies on stealth in order to catch its prey. It doesn't have the luxury of turning down a meal, and the younger dragons are not excluded from the menu.
More: Komodo National Park

Crocodiles
Some species, like the croc, use cannibalism to regulate their population. Larger crocs prey on the juveniles, which keeps their numbers stable, and their other food sources and resources from becoming scarce.
More: Freshwater Crocodile

Humans
Let's not forget that humans have been known, on occassion, to eat one another. In some cases, it's part of the culture, but other times, it's a matter of survival.
More: Dogs Taste Of Otter