Moko the bottlenosed dolphin
Two pygmy sperm whales had repeatedly beached themselves on Mahia beach in New Zealand and conservationists had trouble trying to get them back out to sea.

That is, until Moko the bottlenosed dolphin, who is well known locally for playing with swimmers in the bay, stepped in (swam in?):

Mr Smith said that just when his team was flagging, the dolphin showed up and made straight for them.

“I don’t speak whale and I don’t speak dolphin,” Mr Smith told the BBC, “but there was obviously something that went on because the two whales changed their attitude from being quite distressed to following the dolphin quite willingly and directly along the beach and straight out to sea.”

He added: “The dolphin did what we had failed to do. It was all over in a matter of minutes.”