Baron Arundell of Wardour, in the County of Wiltshire, was a title in the Peerage of England. It was created in 1605 for Thomas Arundell, known as "Thomas the Valiant", son of Sir Matthew Arundell and grandson of Sir Thomas Arundell and of Margaret Howard, a sister of Queen Catherine Howard. Arundell had already been created a Count of the Holy Roman Empire by Rudolph II in December 1595. He was succeeded by his son, the second Baron. He fought as a Royalist in the Civil War and was mortally wounded at the Battle of Stratton in 1643. His son, the third Baron, was implicated in the Popish Plot and imprisoned in the Tower of London for six years. However, after the accession of James II he was restored to favour and served as Lord Privy Seal from 1687 to 1688. His great-great-great-grandson, the eighth Baron, was an avid collector of art and accumulated immense debts in building and furnishing New Wardour Castle.

Thomas Arundell, 1st Baron Arundell of Wardour was the eldest son of Sir Matthew Arundell of Wardour Castle in Wiltshire, and Margaret Willoughby, the daughter of Sir Henry Willoughby, of Wollaton, Nottinghamshire, and wife Margaret Markham. He distinguished himself in battle against the Ottoman Turks in the service of the Emperor Rudolf II, and was created a Count of the Holy Roman Empire. His assumption of the title displeased Queen Elizabeth, who refused to recognize it, and imprisoned him in the Fleet Prison. In 1605 Arundell was created 1st Baron Arundell of Wardour. In the same year, he was briefly suspected of complicity in the Gunpowder Plot.