Stuart Kyle Duncan (born 1972) is a United States Circuit Judge of the United States Court of Appeals for the Fifth Circuit.

On September 28, 2017, President Donald Trump announced his intent to nominate Duncan to an undetermined seat on the United States Court of Appeals for the Fifth Circuit.

On October 2, 2017, he was officially nominated to the seat vacated by Judge W. Eugene Davis, who took senior status on December 31, 2016.

On November 29, 2017, a hearing was held on his nomination before the Senate Judiciary Committee

On April 24, 2018, his nomination was confirmed by a vote of 50–47.