Donald Eugene Nehlen (born January 1, 1936) is an American former college football player and coach. He was head football coach at Bowling Green State University (1968–1976) and at West Virginia University (1980–2000). Nehlen retired in 2001 with a career head coaching record of 202–128–8 and as the 17th-winningest coach in college football history. He was inducted into the College Football Hall of Fame in 2005 and has served as a president of the American Football Coaches Association.

Nehlen was a multi-sport athlete at Lincoln High School (Canton, Ohio) where he excelled in football, basketball, and baseball.

Nehlen played quarterback at Bowling Green (1955–1957) and led the team to a Mid-American Conference championship in 1956. He began his coaching career in 1958 at Mansfield Senior High School and then served as head coach at Canton South High School and Canton McKinley High School. Nehlen was later an assistant coach at the University of Cincinnati, Bowling Green, and the University of Michigan.

Since his retirement from coaching, Nehlen has been a spokesman for the coal industry. Nehlen received the 2002 Distinguished West Virginian Award from the West Virginia Broadcasters Association. In 2006, Nehlen published a book called Don Nehlen's Tales from the West Virginia Sideline, an autobiographical account recalling his 21-year tenure as the head football coach at West Virginia.

In 2017 the AFCA presented Nehlen the Amos Alonzo Stagg Award, given to the "individual, group or institution whose services have been outstanding in the advancement of the best interests of football."

Nehlen served as the quarterbacks coach at the University of Michigan under Bo Schembechler from 1977 to 1979 before taking the head coaching job at West Virginia. Nehlen became West Virginia's 29th head football coach on December 7, 1979, replacing Frank Cignetti, who had posted four straight losing seasons.

Nehlen first hired Gary Tranquill as the offensive coach. In an effort to emulate the Michigan defense, Nehlen hired Dennis Brown away from the Wolverines. Nehlen hired a number of coaches he worked with at Bowling Green. Nehlen also retained Donnie Young, Cignetti's former assistant head coach, as his recruiting coach. Tranquill left West Virginia after three seasons to become head coach at Navy, taking graduate assistant Steve Dunlap with him. Dunlap later returned to serve as West Virginia's defensive coach. One of Nehlen's most famed assistants was Doc Holliday, who served the assistant head coach and recruiting coach for almost 20 years before leaving for North Carolina State University. Holliday was sent to Florida every year to find recruits and found many talented players there, including linebacker Steve Grant. When Nehlen arrived at West Virginia, he introduced the Mountaineers' first "home and away uniforms" and a new helmet logo, "The Flying WV," which became the official logo of West Virginia athletics and, eventually, the university itself.

In 1980, Nehlen's first season at West Virginia, the Mountaineers went 6–6. In 1981, led by quarterback and future WVU athletic director Oliver Luck, West Virginia went 9–3 and upset the Florida Gators in the Peach Bowl, 26–6. In 1982, led by quarterback Jeff Hostetler (who ended up marrying Nehlen's daughter, Vicky), West Virginia started the season with an upset over the #9 Oklahoma Sooners. In 1984, Nehlen's squad posted wins against Boston College, led by eventual Heisman Trophy winner, Doug Flutie, and over Penn State for the Mountaineers' first defeat of the Nittany Lions since 1955.