Rotor Walrus is a Mobian walrus and was a key member of the Knothole Freedom Fighters, using his skills and knowledge of technology and mechanics to provide the Mobians with an edge against the forces of Dr. Eggman. After being injured saving Tails the Fox from a collapsing roof, he became a member of the new Council of Acorn. However, when Ixis Naugus' manipulations resulted in Nicole being unjustly banished from New Mobotropolis, Rotor immediately resigned from the Council in disgust and returned to full field duty as the leader of the new Team Freedom.

Has a cannon voice. For reference, check here (skip to 1:02 in video for voice reference):

https://www.youtube.com/watch?v=JubzKEniPBE