As of 2011, only someone born in 1911 or earlier could be a centenarian. According to the list complied on Memory Alpha about the Early Production History, 67 people associated with Star Trek were born before 1911. All 67 of those people have passed on, but only 1 lived over 100:
"Viola Kates Stimpson (25 October 1906 – 14 January 2008; age 101) is the actress who played the tour lady who points out a possible reason for George and Gracie's whale song in Star Trek IV: The Voyage Home."
Looking to the future, the oldest currently living Star Trek associate is Norman Lloyd, the actor who played Professor Richard Galen in ST:TNG "The Chase." Lloyd was born on 8 November 1914, making him 96 years old.
Actually, the oldest currently-living Star Trek associate is Olaf Pooley, the actor who played a Cleric in the Star Trek: Voyager" episode "Blink of an Eye". Pooley was born on 13 March 1913, making him 99 years old.
Should he reach his 100th birthday, he would be only the second centenarian in the "Star Trek" franchise (behind Viola Kates Stimpson), and the first male centenarian. He would also be the second centenarian in the "Doctor Who' franchise (having appeared in the 1970 story "Inferno"), behind actress Zohra Sehgal (who appeared in "The Crusade"), as well as the first male centenarian in that show as well!