Simplify the following text for a Grade 12 native English-speaking person.
Original: He has acted in several television series in a career of more than fifty years , including his roles as Bret Maverick in the popular 1950s western-comedy series , Maverick and Jim Rockford in the popular 1970s detective drama , The Rockford Files .
Simplified: He has starred in several television series spanning a career of more than five decades . These included his roles as Bret Maverick , in the popular 1950s western-comedy series , Maverick ; Jim Rockford , in the popular 1970s detective drama , The Rockford Files ; and the father of Katey Sagal 's character on 8 Simple Rules following the death of John Ritter .