Well lets see what old characetrs there are in the FF series;
Final Fantasy IV -Tellah is 60 years old and is the 2nd oldest playable character in the FF series.
-Cid is 56 years old in this game(not the Cid from FFVII.)
Final Fantasy V -Galuf is 50 years old.
Final Fantasy VI -Cyan is 50 years old.
-Strago is 70 years old! maybe the oldest playable character in any FF game.
Final Fantasy VII -Barrett is 35 but 37 in Advent Children.
-Red XIII is 48 in human years.
-Vincent is 27 physically but 57 chronologically and 60 in Dirge of Cerberus.
Final Fantasy VIII -Edea her age is unknow but if she raised most of the characters when they were young she must be abit old maybe in her late 30's.
Final Fantasy IX -The oldest character is Steiner who is 32 and not that old really(the same age as Cid in FFVII.)
Final Fantasy X/X-2 -Auron is 35 years old.
Final Fantasy XII -Fran is over 50 years old.
-Reddas age is unknown but from the looks of him he looks old.