Simplify the following text for a Grade 6 native English-speaking person.
Original: Iggy Pop ( born James Newell `` Jim '' Osterberg , Jr. ; April 21 , 1947 ) is an American singer , songwriter , musician , and occasional actor .
Simplified: James Newell Osterberg , Jr. ( born April 21 , 1947 ) , better known by his stage name Iggy Pop , is an American rock singer , songwriter , and sometimes an actor .