Polar bear

The Polar Bear is a mammal that lives in icy, cold places all around the world. It's first appearance was in the Total Drama World Tour theme song.

Theme Song
In the Total Drama World Tour theme song, the polar bear is seen scaring Lindsay, who is holding a picture of Tyler. It is revealed to only be Izzy in a polar bear suit. This is most likely a reference to when Izzy dressed up as a bear to scare her teammates in The Sucky Outdoors in Total Drama Island. After this, Izzy is attacked and bitten by a Baby Seal and runs away, still in the costume.

Anything Yukon Do, I Can Do Better
The polar bear makes its first official appearance in Anything Yukon Do, I Can Do Better. During the first challenge, the contestants must cross an ice floe. When Owen and Cody climb on to the same ice flow, a polar bear emerges from the freezing water and tips their ice flow so the two would fall towards it. Before the polar bear can attack them, Sierra gets the polar bear to go away by throwing ice blocks at it, giving it a huge bump on the head.

Aftermath: Bridgette Over Troubled Water
A clip is shown on, "That's Gonna Leave a Mark," is of Tyler falling on the ice floes in the Yukon. A polar bear watches this and cringes seeing what happens to Tyler. Then, the polar bear covers the eyes of its cub who was also watching Tyler fall.

Aftermath: Revenge of the Telethon
The polar bear is shown during the "DJ's World of Animals" segment, showing that in Newfoundland, when DJ got his team's boat to work, he crashed onto an iceberg with a polar bear on top of it. The iceberg then starts to break apart, before a helicopter falls on top of the polar bear, injuring it.

African Lying Safari
While the bear itself is not present in this episode, during Cody's hallucination brought on by the love-me tea, he imagines Sierra is a polar bear trying to attack him.

Trivia

 * The polar bear is one of three types of bears seen in the show, the others being the brown and black bear.