Penny Wise was a nickname used for Jon Vitti in "Another Simpsons Clip Show" and "The Simpsons 138th Episode Spectacular". According to the DVD commentaries for the respective episodes, he used the pseudonym because he did not want to be credited for writing a clip show. Despite the previous statement, he was credited as himself for "So It's Come to This: A Simpsons Clip Show".
Simpsons Wiki