Fellows moved on to Butler Community College, where he played as a cornerback for two seasons. He also ran the hurdles. He transferred to the University of Missouri after his sophomore season. Midway through the 1979 season, he was converted into a wide receiver, posting 4 receptions for 44 yards and no touchdowns. As a senior, he led the Big Eight Conference in receiving with 587 yards on 33 receptions, while also catching 4 touchdowns.
Fellows was selected by the Dallas Cowboys in the seventh round of the 1981 NFL draft, with the intention of playing him at cornerback. By the eleventh game of his rookie season, he was being used on the nickel defense. The next year he played right corner on obvious passing downs, with starter Dennis Thurman being moved to safety. He also led the team in punt and kickoff returns. In 1983, he played nickel cornerback over former first-round draft choiceRod Hill, while posting 5 interceptions. Against the New Orleans Saints he returned a blocked field goal for a game winning 62-yard touchdown, the first such return by a Cowboy in 19 years. Against the Minnesota Vikings he returned an interception for a 58-yard touchdown. He also tied a team record with 43 kickoff returns. Fellows was part of an opportunistic Cowboys secondary that earned the nickname "Thurman's Thieves", because of the amount of plays and turnovers they generated. In 1985, he became the starter at right cornerback opposite of Everson Walls. In 1984, after Thurman made the permanent switch to safety, he became the starter at right cornerback opposite Everson Walls, and posted 3 interceptions. The next year he struggled with a sprained knee he suffered in the first quarter of the season opener against the Washington Redskins, that caused him to miss 3 games and 2 starts, eventually requiring offseason surgery. He still managed to make 4 interceptions and 20 passes defensed. In 1986, he finished first on the team with 15 passes defensed and second on the team with 5 interceptions, including a 34-yard return for a touchdown against the St. Louis Cardinals. Against the Chicago Bears, he accounted for 4 turnovers. On August 2, 1987, after being involved in a contract holdout and with the Cowboys needing help at wide receiver, the team felt they had depth at cornerback after drafting Ron Francis, so he was traded to the Los Angeles Raiders in exchange for Rod Barksdale.
Los Angeles Raiders
In 1987, Fellows was the team's nickel cornerback, appearing in 12 games with 2 starts. He was waived on August 29, 1988, but was re-signed after Terry McDaniel was lost for the year with a broken leg in the second game of the season. He appeared in 14 games with 10 starts at left cornerback, registering 2 interceptions and 2 fumble recoveries. He was not re-signed after the season.
After football
Fellows married wife Debra in 2002 and founded the Stars for Life Foundation, a nonprofit aimed at serving Native American communities suffering from addiction, diabetes and suicide. It now educates the public on the long-term dangers of impact sports. He was diagnosed with Alzheimer's disease in 2015.
