Complex sentence: Grant Sullivan (June 30,1924--May 31,2011) was an American actor best known for starring as the investigator Brett Clark in the television series, "Pony Express", which aired in syndication from 1959 to 1960.
Split into simpler sentences: Grant Sullivan (June 30,1924--May 31,2011) was an American actor best known for starring in the American television series, "Pony Express". Sullivan portrayed the investigator Brett Clark in "Pony Express", which aired in syndication from 1959 to 1960.