Fiona Mary Petty-Fitzmaurice, Marchioness of Lansdowne, DL (née Merritt; born 3 October 1954), previously known professionally as Fiona Shelburne, is a British aristocrat, socialite and interior designer.

Born in 1954, Fiona Merritt married in 1987, as his second wife, Charles Petty-Fitzmaurice, Earl of Shelburne.

[1] She was styled Countess of Shelburne by courtesy until her husband succeeded to his father's titles in 1999.

She first met her husband (then Lord Shelburne) on a working visit to Bowood while employed by Charles Hammond in the early 1980s.

[8] She was one of her two ladies in attendance, alongside the Queen's sister Annabel Elliot, at the coronation on 6 May 2023.