Yawk is a one-shot minor antagonist of the reboot TV series, Ben 10. He first appeared in the episode, Mayhem in Mascot.
Yawk used to be an ordinary bear, but he got cursed. As a result, he turns into a wooden statue during the day. In order to break the curse, he should escape the valley during sunrise.
Mayhem in Mascot
It is stated that the bear statue should be covered in cloth when it is night time. Ben and Gwen opened the cloth and the bear came to life. He told them that he needs help for his curse to break. Other statues also came to life to stop Yawk. Ben and Gwen helped him escape. Once he is about to go up the pile of rocks. Ben, who transformed into an alien destroyed the rocks and Yawk fell. Since that is day time and he fell to the valley, he turned into a statue and broke.
Yawk's statue form is made of wood. During the night, he looks like a normal bear, but can talk. His evil form is more creepy, since he has red eyes.
Yawk is a traitor. He asks help from others without letting them know he is evil. He is actually a very brutish and feral type.