Oswald Martyn (10 January 1887 – 14 September 1959) was an English cricketer who played for Essex.
He was born in Clapham and died in Patcham.
Martyn represented Essex in one first-class match, against Northamptonshire during the 1922 County Championship season.
An upper-middle order batsman, his sole contribution to the match was a duck with the bat in the Essex first innings.