Willie Stargell hit the ball out of the park.
Ted William's longest home run in Fenway Park was 502 feet, but I don't know if that was his longest home run ever.
The longest home run was made by Ryan Howard. 536 ft.
Ronnie Green of the KC Royals hit the longest home run at Fenway Park in 1987
Reggie Jackson
Reggie Jackson hit career home run number 500 on September 17, 1984 off Royals pitcher Bud Black, in the bottom of the 7th inning in California.
The longest home run of 2009 belongs to Waldemar Balentien of the Cincinnati Reds. It was measured at 495 ft.
Justin Upton
507 feet by prince fielder
Reggie Jackson hit career home run number 400 on August 11, 1980, off White Sox pitcher Britt Burns, in the bottom of the 4th inning at Yankees Stadium.
603 ft
760 ft.
405'