John Grigas was born on August 19, 1920 in Chelsea, Mass and attended Chelsea High School.

After graduation he played football for Holy Cross from 1940-1942. In 1941 he was selected on the All-American second team and ranked third nationally with 709 rushing yards. In 1942, he scored four touchdowns in a 55-12 upset of rival Boston College and went on to play in the Blue-Grey Football Classic.

He was drafted in the 2nd round by the Chicago Cardinals in the 1943 NFL Draft, but reported for his physical for induction to the Army and was rejected.

He played fullback for the Cardinals in 1943 and 1944, where he rushed for 943 yards and caught 21 passes for 258 yards and also passed for 788 yards. He was named to the All-NFL first team in 1944, and led the NFL with 1154 all purpose yards.

Having quit the Cardinals, who hadn't won a game in his two years, he joined the Boston Yanks and played fullback in 1945. He carried 64 times for 160 yards, and caught 5 passes for 59 yards and scored two touchdowns. The following year was his best as he had 84 carries for 426 yards and caught 3 passes for 61 yards, scoring three touchdowns. In his final year for the Yanks in 1947, he had 27 carriers for 52 yards, but had missed a good part of the season with injuries.

After his retirement from professional football, he worked for 35 years as an industrial engineer at American Optical, in Southbridge, Mass.

In 1976, he was elected to the Holy Cross Varsity Club Hall of Fame.

John Grigas died on May 19, 2000 at age 74, in Worcester, Mass.