April Derp is a malformed clone of April O'Neil. She exhibits super strength, but an incredibly low intelligence. She has a vocabulary that consists almost solely of the word "derp".
April Derp is referred to by the Kraang as a "reject", an obvious prototype or imperfection compared to the dozens of other April Clones that they had developed. Still, due to her magnificent strength, she is played as a trump card against the Turtles during their invasion of TCRI.
April Derp is killed by a psychic pulse from the real April.