Louis Emory McComas (b. October 28, 1846, d. November 10, 1907) was a Republican member of the United States Senate, representing the State of Maryland from 1899-1905.

McComas was born near Hagerstown, Maryland. He attended St. James College in Maryland and, in 1866, graduated from Dickinson College in Carlisle, Pennsylvania. In 1868, after studying law, McComas was admitted to the bar and began practice in Hagerstown.

In 1876, McComas was defeated in his bid for a seat in the Forty-fifth Congress, but after nearly a decade out of politics, McComas was successfully elected in 1882 to the Forty-eighth and to the three succeeding Congresses. He was an unsuccessful candidate for reelection in 1890 to the Fifty-second Congress.

Following his tenure in Congress, McComas served as secretary of the Republican National Committee 1892. On November 17, 1892, he was appointed by President Benjamin Harrison an Associate Justice of the Supreme Court of the District of Columbia, which he held until 1899. He also served as a professor of international law at Georgetown University in the District.

McComas was successfully elected to the United States Senate in 1898. While senator, he served as chairman of the Committee on Organization, Conduct, and Expenditures of Executive Departments (Fifty-sixth Congress) and as a member of the Committee on Education and Labor (Fifty-seventh and Fifty-eighth Congresses).

McComas did not run for a second term in the Senate after being appointed by President Theodore Roosevelt as a justice of the Court of Appeals of the District of Columbia in 1905. He served in that position until his death in Washington, D.C. in 1907, and is buried in Rose Hill Cemetery in Hagerstown.