Rupert Maas (born 1960) is an English painting specialist and gallery owner, known for his numerous media and television appearances.
Maas was born in 1960. His father, Jeremy Maas, started the Maas Gallery in Mayfair, London, dealing in Pre-Raphaelite paintings, writing a book in 1969, Victorian Painters. Rupert Maas was educated at Sherborne School in Dorset from 1974 to 1978, and took a BA in Art History at the University of Essex from 1980 to 1983. 
In the summer of 1983 he sailed the Atlantic and later that year joined the Maas Gallery. In 1997, following the death of his father, Maas became director of the gallery, which deals in Victorian, Pre-Raphaelite, Romantic and Modern British paintings, watercolours, drawings, reproductive engravings and sculpture. The gallery has also featured the work of a number of contemporary living artists, including Keiron Leach and Julia Sorrell.
Maas served on the executive committee of the Society of London Art Dealers in 1998–99. He co-owns and runs The Watercolours and Drawings Fair. He has regularly written articles for the arts press and lectures on art. He is widely recognised as the leading expert on the works of the Royal Academician Augustus Leopold Egg (1816–1863). He also promotes Ballantine's whisky in the Far East.
Maas is frequently called upon to provide independent valuations for museums, both domestic and international, and has previously valued individual pictures and entire collections (for example the John Wharlton Bunney 1828-1882 archive) for Acceptance in Lieu. In 2006 Maas was duped into paying £20,000 for a faked art work claimed to be by fairyland painter John Anster Fitzgerald (1823–1906).
Since 1997 Maas has appeared on BBC's Antiques Roadshow and on Castle in the Country as a picture specialist, and has appeared regularly on other television programmes. In late 2008 he caused a minor local controversy when he implied, in an episode of Antiques Roadshow, that women from Shropshire had fat ankles.
Known for his ability to reel off spontaneous art-related witticisms, one of his best known and oft-quoted quips pertains to vetting an artwork's authenticity by bearing in mind that "Everything but the naked picture is capable of lying."
- "About us". Maasgallery.co.uk. Retrieved 2014-05-25.
- "The pre-Raphaelites: behind the scenes at a modern blockbuster". The Observer. 19 August 2012. Retrieved 31 May 2015.
- "Jail for forger who conned Antiques Roadshow host", Daily Mail, 18 September 2006
- "WI fights back over 'fat ankle' jibe". The Independent. 30 November 2008. Retrieved 31 May 2015.
- "It's official - county ankles are super!", Shropshire Star, 3 December 2008