 Dave Karofsky is played by actor Max Adler , who first appeared in the first season episode " Mash @-@ Up " , initially as a member of the William McKinley High School hockey team . Karofsky began as a background character who tormented members of the glee club , and was known only by his surname . So far as Adler knew , his role was for a single episode only , but he returned once more before the first half of the first season ended , and then three times in the nine episodes of the second half of that season . The last of these , " Theatricality " , written and directed by series co @-@ creator Ryan Murphy , proved to be pivotal : Murphy was impressed with his acting and wanted to write more for him . 
