Luna the whale and dog

The killer whale is Luna, who showed up in Nootka Sound, Canada in 2001.

Moko the dolphin saves beached whales

A March 2008 story from the BBC:

A dolphin has come to the rescue of two whales which had become stranded on a beach in New Zealand. Conservation officer Malcolm Smith told the BBC that he and a group of other people had tried in vain for an hour and a half to get the whales to sea.

The pygmy sperm whales had repeatedly beached, and both they and the humans were tired and set to give up, he said. But then the dolphin appeared, communicated with the whales, and led them to safety.

Read more at Times Online.