Named after George Orson Welles - American radio and motion picture actor and director (1915-1985).
He is famous for, among other things, his radio broadcast of The War of the Worlds by H. G. Wells in which Martians invade Earth. (wikipedia entry)
A crater is a circular depression likely created by an impact event. On Mars large craters are named after deceased scientists, writers and others who have contributed to the lore of Mars. Small creaters (less than 60km) are named after small towns and villages.