Horace Emerson Deemer (September 24, 1858 – February 26, 1917) was a justice of the Iowa Supreme Court from May 8, 1894, to February 26, 1917, appointed from Montgomery County, Iowa. His service included four years as chief justice.^[1][2][3]

Born in Bourbon, Marshall County, Indiana, Deemer was the eldest of six children. The family came to Iowa in 1866, settling on a farm near West Liberty, in Cedar County.^[3]

Deemer received his law degree from the University of Iowa in 1879, commencing the practice of law in Red Oak, Iowa. He was elected to a seat on the state district court in 1886, and was appointed to the Iowa Supreme Court on May 8, 1894, following passage of a law adding a sixth justice to the court.^[1][2][3] In 1911, Deemer's name was put forward as a candidate for appointment to the United States Senate, to a seat vacated by the death of Senator Lafayette Young, but William S. Kenyon was chosen instead.^[3] Deemer remained on the court thereafter until his death, in Red Oak, at the age of 66.^[1][2][3]