From http://en.wikipedia.org/wiki/Eugene_Cernan:
"...as lunar module pilot of Apollo 10 in May 1969; and as commander of Apollo 17 in December 1972. In that final lunar landing mission, Cernan became "the last man on the moon" since he was the last to re-enter the Apollo Lunar Module during its third and final extra-vehicular activity (EVA). (While crewmate Harrison Schmitt was "the last man to arrive on the moon" as Cernan left the module first). Cernan was also a backup crew member for the Gemini 12, Apollo 7 and Apollo 14 missions."
AND from http://en.wikipedia.org/wiki/Edgar_Mitchell:
"Edgar Dean Mitchell, D.Sc. (born September 17, 1930) is an American pilot, engineer, and astronaut. As the lunar module pilot of Apollo 14, he spent nine hours working on the lunar surface in the Fra Mauro Highlands region, making him the sixth person to walk on the Moon."
If you don't get the facts, anyone can check, correct, it is hard to make yourself believable.
I meant to say “longest”...it came out wrong. Sorry.