Cap Anson and Nolan Ryan each played for 27 seasons. Cap from 1871 to 1897 and Ryan from 1966 to 1993.
(see Baseball-reference.com's article "Most Seasons Played"
http://www.baseball-reference.com/leaders/leaders_most_seasons.shtml )
George Blanda holds the record playing 26 NFL Seasons as a kicker.
Jesus and god they drew
Robert Parish - 21 seasons (1976-1997)
No surprise -- Cy Young holds the record at fifteen seasons of 20 or more wins.
Nolan Ryan.
Morten Andersen, with 368 games in 24 seasons. George Blanda played for 26 seasons but only played in 340 games.
Nolan Ryan
There are many players in the NFL that currently hold records. Records are often broken. As of July 2013 George Blanda holds the record for the most seasons played. He also holds the record for the most decades played.
Patriots
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Walter Payton
Hoyt Wilhelm and John Franco, each recording at least 1 save in 19 seasons. Franco played for 21 seasons (1984-2001, 2003-2005) and failed to record a save in 2004 and 2005. Wilhelm played for 21 seasons (1952-1972) and failed to record a save in 1955 and 1959.