Marquess of Headfort is a title in the Peerage of Ireland, created in 1800 for the Earl of Bective.

The Marquess holds the subsidiary titles of Earl of Bective (1766), Viscount Headfort (1762), Baron Headfort (1760), and Baron Kenlis (1831), all but the last in the Peerage of Ireland. He is also an Irish baronet.

Before the passage of the House of Lords Act 1999, the Marquess sat in the House of Lords as Baron Kenlis in the Peerage of the United Kingdom.

Earls of Bective (1766)

• Thomas Taylour, 1st Earl of Bective (1724-1795)
• Thomas Taylour, 2nd Earl of Bective (1757-1829), elected a Representative Peer in 1800, and became Marquess of Headfort later the same year

Marquesses of Headfort (1800)

• Thomas Taylour, 1st Marquess of Headfort (1757-1829)
• Thomas Taylour, 2nd Marquess of Headfort (1787-1870)
• Thomas Taylour, 3rd Marquess of Headfort (1822-1894)
• Geoffrey Thomas Taylour, 4th Marquess of Headfort (1878-1943)
• Terence Geoffrey Thomas Taylour, 5th Marquess of Headfort (1902-1960)
• Thomas Geoffrey Charles Michael Taylour, 6th Marquess of Headfort (b. 1932)