[MorganMiller1926]

None.
While no surviving players appeared in games on Opening Day 1946 (4/16/1946) there are 8 surviving players who appeared in 1946 MLB games. A few players, such as Tommy Brown (Dodgers) appeared in games before 1946, but were in the military in 1946 and appeared in no 1946 MLB games.

Living players who appeared in MLB games in 1946:

Gil Coan (Washington Senators). Played 11 MLB seasons (1946 -1956).
Tom Jordan (Chicago White Sox and Cleveland Indians) - Oldest living major Leaguer. - age 99. Played parts of 4 MLB seasons (1944; 1946 -1948)
Lee Howard (Pittsburgh Pirates). (Played One MLB Season (1946)
Johnny Groth (Detroit Tigers) - Played 15 MLB seasons (1946 - 1960).
Bobby Brown (NY Yankees) - Played 8 MLB Seasons (1946 -1952 & 1954) Played In 4 World Series (1947, 1949, 1950 & 1951).
Eddie Robinson (Cleveland Indians) - Played 13 MLB seasons. (1942 & 1946 -1957) This stellar first baseman played in 4 all-star games and in 2 World Series.
Dick Koecher (Philadelphia Phillies) - Played parts of 3 MLB seasons (1946 -1948).
Don Hasenmayer (Philadelphia Phillies) - Played parts of 2 MLB seasons (1945 -1946).