Isaac Marin (born 13 February 1946) is a Costa Rican boxer. He competed in the men's light welterweight event at the 1968 Summer Olympics.^[1]

Marin competed in 68 professional bouts. Instead of going up in weight like most boxers, Martin went down two weight divisions when he became a professional boxer. Highlights of his career include fighting Antonio Amaya,^[2] beating future world title challenger Francisco Coronado twice,^[3][4] future Alexis Arguello world title challenger Diego Alcala^[4] and Love Allotey,^[5] losing to former world champion Alfonso Frazer^[6] and challenging Ricardo Arredondo for the Mexican's World Boxing Council World Super Featherweight (Junior Lightweight) title, losing to Arredondo in a somewhat controversial and close but unanimous fifteen round decision with scores of 145-146, 142-146 and 141-149 in favor of Arredondo, on January 29, 1972, in the Costa Rican capital of San Jose.^[7] Later on in his career, he lost to Antonio Gomez and to Bazooka Limon.

Marin had 37 wins, 30 losses and 1 draw (tie), with 18 wins by knockout.