The bears are the main antagonists who become enemies of Mike in Sing.
They are voiced by Jim Cummings (credited as James J. Cummings in the film).
The leader bear wears a black leather jacket covering a white shirt, along with a black hat and black pants with a large belt buckle. The second bear wears a black and white jacket and a black flat cap. The third bear wears a light blue jacket covering a dark blue shirt, and appears to have squinted eyes.
The bears enjoy playing cards and gambling at the night club, and are very serious about it. They hate being cheated; when Mike did so, they went to a lot of effort to get the money back from him, and almost ate him.
They are a trio of Russian-accented Bears who got swindled in a card game with Mike when the leader discovers Mike cheated, and they attempt several times to catch Mike to get their money back, only to learn that Mike already spent all of it. The leader almost eats Mike, but he cowardly tells them he can get them $100,000 from Buster Moon.
They trespass in the Moon Theater, threatening Mike's life to get Buster to hand over the money. The bears smash the chest with a baseball bat, only to find the chest holding it contained less than $1,000 and several objects intended to match the intended prize value. The bears and Buster's singers all converge on him. Their combined weight along with the recent damage done by the baseball bat caused the glass tank full of water and squids to break, washing everyone out of the theater and causing it to collapse.
Seeing Mike has escaped, the bears quickly run before they can be connected with the theater's destruction.
Later, after the singers have set up an open air theater to perform, the bears see Mike performing on TV and quickly head over to get their revenge. They manage to swipe Mike without being seen and the leader almost eats Mike again, only for Nancy to come to his rescue in Mike's car.
As they drive off, they don't notice the leader bear is hanging onto the back, sneering.
“Well, you are one great card player, Mike. Except I still can't tell how you cheated.”
–The leader bear after playing a card game against Mike
“And where are you going to get that kind of money?”
–The leader bear questioning Mike after he offers $100,000 to the bears as reparation for cheating