|Date of birth:||February 4, 1917|
|Place of birth:||Redondo Beach, California|
|Date of death:||September 22, 2006 89)(aged|
|Place of death:||Tucson, Arizona|
|Height:||6 ft 3 in (1.91 m)|
|Weight:||200 lb (91 kg)|
|NFL Draft:||1940 / Round: 1 / Pick: 10|
|Career NFL statistics|
A native of Redondo Beach, California, Nielsen attracted interest from the Arizona Wildcats and USC Trojans college football teams. Because he believed the Arizona environment would be better for his asthma, he spurned the local Trojans and accepted an athletic scholarship to play for the Wildcats. Nielsen played for Arizona from 1936 to 1938, and gained the nickname "Hoss" early in his career. In his first two years, under head coach Tex Oliver, he joined fellow future NFL running back Tom Greenfield as part of a team known as the "Blue Brigade". The Wildcats had win–loss records of 7–2 and 5–2–3 in those seasons. Nielsen was named to the Little All-American team in 1937, before a knee injury affected him the next year. In 1939, the Giants selected him with the 10th pick in the NFL Draft, making him the first Wildcats player to be taken in the first round of a draft.
Although the Giants signed Nielsen in July 1939, he spent the 1939 season as a member of the minor league Jersey City Giants, reportedly due to a case of hay fever. In 1940, Nielsen rushed for 269 yards in 73 attempts during the nine games he played in, and his average of 3.7 yards per carry was ninth in the NFL. In addition, he caught two passes for 17 yards and scored one touchdown. He accounted for the Giants' first score in a 37–21 loss to the Chicago Bears on October 27, with a one-yard run.
After 1940, Nielsen did not play another NFL game. He participated in World War II; two days after the Normandy landings, he entered France via Omaha Beach. One newspaper reported that Nielsen went on to join "in a reconnaissance mission", along with "driving armored cars ahead of the Allied tanks to scout out Nazi positions." Following a period in "private business" later in his life, Nielsen died at the age of 89. Nielsen has been named to Arizona's Football Ring of Honor.
- Gimino, Anthony (August 13, 2013). "No. 20: Back Walter Nielsen, 1936–38". The Arizona Republic. Retrieved June 19, 2014.
- Hansen, Greg (September 23, 2006). "Nielsen, UA football All-American in '37". Arizona Daily Star. Retrieved June 22, 2014.
- "Walt Nielsen Signs With Pro-Gridders". Prescott Evening Courier. Associated Press. July 14, 1939. p. 3. Retrieved June 19, 2014.
- "Walt Nielsen". Pro Football Reference. Retrieved June 19, 2014.
- "Chicago Bears 37 at New York Giants 21". Pro Football Reference. Retrieved June 19, 2014.
- "The University of Arizona Sports Ring of Fame". University of Arizona. Retrieved June 22, 2014.