Kearney Zzyzwicz, Sr. (pronounced "jeez-wich") is one of the school bullies of Springfield Elementary, with Nelson Muntz, Dolph Starbeam, Jimbo Jones, and the Weasels. He later became one of Bart Simpson's friends. He is the toughest of the bullies, and is also the 2nd strongest out of the bullies along with Jimbo. He is of Polish descent. He is a 5th grader. (Although in 24 Minutes, Kearney is shown to be missing from the 6th Grade Class).
Kearney has a father named Mr. Zzyzwicz, a mother named Mrs. Zzyzwicz. Kearney is older than Jimbo and Dolph and Kearney has a six-year-old son. He attended school with Otto Mann. Kearney's last name (Zzyzwicz) was revealed in a computer file in season 18's "24 Minutes". Prior to that episode, Kearney's surname was never mentioned. Kearney's surname implies that his family could be of Polish origin. Kearney drives an old style Hyundai. This is evidenced when Principal Skinner attempts to pry off Kearney's hood ornament to replace the 'H' logo stolen from Superintendent Chalmers' Honda. Kearney catches him in the act, forcing Skinner and Chalmers to flee. Kearney is seen smoking in the room where Bart, Nelson, Jimbo, and Dolph are trapped during Superintendent Chalmers's visit.