April is the voice of Liane Cartman, 

Sharon Marsh, Mrs. McCormick,

Shelly Marsh, The Mayor,

Principal Victoria,  Mrs. Crabtree,

Wendy Testaberger and various other characters on

Comedy Central's hit show  South Park

as well as being the voice of Maria on Nickelodeon's Brand new Hit show,

El Tigre: The Adventures of Manny Rivera