There has been a mountain of heartbroken, talented would-be black quarterbacks who were “converted” to defensive backs and wide receivers. Constrained by the wrongheaded notion that brains and extraordinary athletic ability were incompatible, generations of blacks were deemed too talented, in some eyes, to play quarterback or not cerebral enough to play the position.
—  The Undefeated

Over the history of the NFL, which was founded in 1920, black athletes for decades weren’t given a chance to play quarterback. Talented black college quarterbacks, especially those from historically black colleges and universities, were converted to defensive back or wide receiver. But when Doug Williams led the Washington Redskins to the championship 30 years ago and was named Super Bowl MVP, it seemed to end once and for all the odd question of whether black NFL quarterbacks could succeed.
—  Raleigh News and Observer

All these years later, he was still proud of Williams, whose name to some may be that of a half-remembered player from the past but to millions of others remains a powerful symbol of progress. It stayed with me, and it seemed that it was worth telling the story not just of Williams, but of everyone—of all those generations of players who struggled so that Russell Wilson could be, simply, a good young quarterback. So the Deadspin staff set out to find and name every single black quarterback ever to play in the NFL. ... Though black NFL quarterbacks make up one of the smallest fraternities in all of sports, no one anywhere had ever compiled an exhaustive list. No one knows the names of every black quarterback ever to play in the NFL for sure, including us.
—  Deadspin's "Big Book of Black Quarterbacks"

Marlin Briscoe didn’t want to be pigeonholed simply because of stereotypes against black men. He was a star quarterback in college and he believed he had the talent, intelligence and leadership skills to be one in the pros. Fifty years ago, during an era of massive social upheaval in the United States, just getting a chance to prove it took a risky ultimatum. ... Briscoe’s groundbreaking accomplishments were somewhat lost in the shuffle during one of the most transformative years in U.S. history. ... But Briscoe’s legacy resonates among his contemporaries 50 years later, hitting on race as well as the pressures athletes face in pro sports. The Pro Football Hall of Fame calls Briscoe the first African-American starting quarterback in modern pro football history. Carolina’s Cam Newton and Seattle’s Russell Wilson have both considered Briscoe’s past as they contend for championships. Doug Williams, the first black quarterback to win a Super Bowl, counts Briscoe as one of his most important inspirations.
—  AP News

It’s not a secret that the quarterback position in the NFL has historically been dominated by white players. ... Despite the lack of black starting quarterbacks in the past, there were certainly many players who paved the way for these aforementioned names. Here is a list of the best black quarterbacks of all time.
—  Complex

It is no secret that in the early days of the NFL, the owners and coaches were very reluctant to give the reigns of a team to a black player. As recently as 2007, the New York Giants had never had a black quarterback throw even a single pass. In 1934, there was an informal ban on black athletes. ... Still, the abolishing of the ban did not do a whole lot to help enable blacks to play the quarterback position. ... After [Doug] Williams' selection, there was a drought for black QBs entering the league. It took five more years to see another black player drafted for the quarterback position. It wasn't until the 1980s that the black quarterback became a little more acceptable, yet still not very common. As the 80s and 90s progressed, however,  so too did the acceptance of black quarterbacks.
—  The Sporster