- When the Gastornis chick is eaten alive by ants is an odd mixture of this and Nightmare Fuel.
- The mother Gastornis coming back to the nest and discovering that her baby is dead. Her reaction is to huff quietly then walk away. For a moment, you really feel sorry for this giant predatory flightless bird — and as of 2014, it's not even predatory. It was discovered to be a complete herbivore.
- The australopithecines "mourning" their elder female in "Next of Kin", probably because of how human they look.
- The mother bear dog whimpering while she digs her dead pups out of the collapsed den.
- The mother brontothere seen anxiously watching her dead calf. Especially heartbreaking is the fact that her brain is too small to even understand the concept of death, so she continues to guard the corpse of her baby and defend it from predators as though it were alive.
- The poor Moetherium getting stranded on the sandbar, with the hungry Basilosaurus lurking in the lagoon waiting for the tide to come in so it can kill and eat it. Even though it escapes its predator, the moment where the camera pans out to show the Moetherium stranded while the Basilosaurus swims around it feels pretty hopeless.
- The mother Indricothere aggressively chasing off her young, since she's due to have a new baby soon, and her maternal instincts have now transferred over to her unborn young. The current young Indricothere can't understand why his mother is so hostile and can only dejectedly run away.
- Later on, the young Indricothere injured while out on his own, prompting him to return to his mother. He returns to find his mother with the new baby, but she sees her previous offspring as nothing as a threat. The young Indricothere is once again violently driven off by his own mother. What's worse is that earlier, the same thing happened to him, as he witnessed his mother's previous young being chased off, and the narrator made it clear that he was looking at his own future - and the new young is doing the same. It's also worth noting that this practice occurs among modern-day rhinos as well.
- Half-Tooth exploring his usurped territory in the rain, only to find the severed head of one of his last cubs. The narrator makes it clear that this signifies the completely severed ties between Half-Tooth and his former pack, and the completion of the brothers' take-over.
- The opening of the final episode where one mammoth falls into a frozen lake and is stuck. Her herd immediately doubles back, and when they fail to free her, they stay with her, comforting her for as long as they can. But eventually, they have to leave her behind to the mercy of a growing group of predators, and continue their journey.
- The matriarch of the herd is driven off a cliff by the Neanderthals, and she gives the most horrid scream as she falls to her death. What's worse is that she and the other mammoth who fell aren't even dead yet, and can only tremble helplessly as the Neanderthals put them out of their misery only so that they can feast.
- The final scene of the series, transitioning from an early modern human carving a mammoth figurine to a prehistoric museum displaying the same item, can be pretty haunting. A stark reminder that these magnificent animals are long gone, and so humans too will one day perish.
Tear Jerker / Walking with Beasts