Timothy Aidan John Knox FSA (born 9 August 1962) is a British art historian and museum director. Since 2013 he has been the Director of the Fitzwilliam Museum in Cambridge.
He was educated at Ratcliffe College, Leicestershire, and took a BA at the Courtauld Institute of Art. In 1989 he was appointed Assistant Curator at the Royal Institute of British Architects Drawings Collection. In 1995 he joined the National Trust as its Architectural Historian and in 2002 became that organisation's Head Curator. Among the projects with which he was involved were the restoration of the gardens of Stowe House, the acquisition of Tyntesfield and of the Workhouse in Southwell, Nottinghamshire, and the restoration of the Darnley Mausoleum in Cobham Park, Kent.
From 2005 to 2013 he was Director of Sir John Soane's Museum in London, where he oversaw a restoration project of Nos. 12 and 14. Lincoln's Inn Fields, the two houses flanking the original house-museum created by the Georgian architect Sir John Soane. Since 2009 he has been a member of the editorial board of the Georgian Group. He has been Vice-Patron of the Public Monuments and Sculpture Association since 2012.