Dame Penelope Alice Wilton DBE (born 3 June 1946) is an English actress. She was formerly married to fellow actor Sir Ian Holm, and as she has not remarried, she retains her married style of Lady Holm.

Wilton is known for starring opposite Richard Briers in the BBC sitcom Ever Decreasing Circles (1984–1989), playing Homily in The Borrowers (1992) and The Return of the Borrowers(1993), and for her role as the widowed Isobel Crawley in the ITV drama Downton Abbey (2010–2015). She also played the recurring role of Harriet Jones in Doctor Who (2005–2008) and Anne in Ricky Gervais' Netflix dark comedy After Life.