David Patterson Dyer (February 12, 1838 – April 29, 1924) was a United States federal judge and U.S. Representative from Missouri. He was also the uncle of U.S. Representative Leonidas C. Dyer.
Born in Henry County, Virginia, Dyer moved with his parents to Lincoln County, Missouri, in 1841. He completed preparatory studies, went to St. Charles College, studied law in Bowling Green, Missouri, and was admitted to the bar in March 1859. He then went into private practice of law in Pike County, Missouri.
Dyer was elected prosecuting attorney of Third Judicial Circuit Court in 1860. During the Civil War he served as a private in Captain Hardin's company, Pike County Regiment, Missouri Home Guard, and as lieutenant colonel and colonel in the Forty-ninth Regiment, Missouri Volunteer Infantry. He served as member of the Missouri House of Representatives from 1862 to 1865. He was Secretary of the Missouri Senate in 1866. He served as delegate to the Republican National Convention in 1868.
Dyer was elected as a Republican to the Forty-first Congress (March 4, 1869 – March 3, 1871), representing Missouri's 9th congressional district. He was an unsuccessful candidate for reelection in 1870 to the Forty-second Congress, and resumed the practice of law in St. Louis, Missouri. He was a United States Attorney for the Eastern District of Missouri from 1875 to 1876, and was an unsuccessful Republican candidate for Governor of Missouri in the 1880 election. He was appointed by President Theodore Roosevelt to again be the U.S. Attorney for his district, and served from March 9, 1902, to March 31, 1907.