Sir John Ennis, 1st Baronet (1809 – 8 August 1878) was an Irish Independent Irish and Liberal politician who sat in the House of Commons from 1857 to 1865.
In 1857 Ennis was elected Member of Parliament for Athlone for the Irish Independent Party. In 1859 he was re-elected as a Liberal and held the seat until 1865.
Ennis was created a baronet in 1866. He was a director of the Bank of Ireland and lived at Ballinahown Court, Athlone. In the 1870s, he owned estates of 8,774 acres (35.51 km2) in Westmeath, 326 acres (1.32 km2) in county Dublin and 262 acres (1.06 km2) in Roscommon. He died at the age of 69
Ennis married Anna Maria Henry, daughter of David Henry of Dublin. His only son John was also MP for Athlone and succeeded to the baronetcy.