Here's my source:
https://acsweb.ucsd.edu/~ptchir/
John Lysak is the oldest living Olympic Games participant. He will turn 106 years old in August.
Folke Alnevik is the oldest living Summer Oympic medallist (bronze in 4x400 relay 1948). He turned 100 years old on New Year's Eve.
Agnes Keleti is the oldest living Olympic champion. She is actually older than Elda Cividino but only made her Olympic debut in 1952, some 16 years after Cividino.
Celina Seghi is the oldest living Winter Games participant (4th in downhill & combined in St. Moritz 1948). She turned 100 years old in March.
Carl-Erik Asplund is the oldest living Winter Olympic Games medallist (bronze in 10,000 speed skating 1952).
Viktor Shuvalov is the oldest living Winter Olympic champion (Ice Hockey center, 5 goals/2 assists in the 1956 Games).
Apparently all the medallists from St. Moritz 1948 are no longer alive. The last Oslo 1952 champion passed away in April of last year ( Lydia Wideman, gold in 10km cross country).