Baron Arlington is a title in the Peerage of England. In 1664, it was created for Sir Henry Bennet, with a special remainder allowing it to descend to male and female heirs, rather than only male heirs, as was customary with most peerages. In 1672, he was made Earl of Arlington and Viscount Thetford, and was regranted the title of Baron Arlington, with the same special remainder.

The first Earl died without male heirs, so the titles went to his daughter Isabella, Duchess of Grafton. At age four, Isabella was married off to the nine-year old Duke of Grafton, an illegitimate son of King Charles II. After the death of the couple, Charles Fitzroy, their son, came to hold both the Arlington and Grafton titles. The two sets of titles continued united until the death of the ninth Duke in a racecar accident in 1936. The dukedom passed to a cousin, while all of the Arlington titles fell into abeyance between his two sisters, neither of whom petitioned the Sovereign to terminate the abeyance. After the death of the elder sister, her elder daughter Jane did petition the Crown, and the abeyance of the barony of Arlington created in 1664 was terminated in her favour. The barony of Arlington created in 1672, however, remains abeyant, along with the earldom of Arlington and the viscountcy of Thetford. These titles offer the only example of a peerage other than a barony falling into abeyance.

Barons Arlington (1664)

• Henry Bennet, 1st Earl of Arlington (1618-1685)
• Isabella Bennet, 2nd Countess of Arlington (c. 1668-1723)
• Charles Fitzroy, 2nd Duke of Grafton (1683-1757)
• Augustus Henry Fitzroy, 3rd Duke of Grafton (1735-1811)
• George Henry Fitzroy, 4th Duke of Grafton (1760-1844)
• Henry Fitzroy, 5th Duke of Grafton (1790-1863)
• William Henry Fitzroy, 6th Duke of Grafton (1819-1882)
• Augustus Charles Lennox Fitzroy, 7th Duke of Grafton (1821-1918)
• Alfred William Maitland Fitzroy, 8th Duke of Grafton (1850-1930)
• John Charles William Fitzroy, 9th Duke of Grafton (1914-1936) (abeyant 1936)
• Jeniffer Jane Forwood, 10th Baroness Arlington (b. 1939) (abeyance terminated 1999)