The Right Honourable Dame Mary Howarth Arden (born January 23, 1947), styled Lady Justice Arden, was named to the Court of Appeal of England and Wales in October 2000, replacing Sir John Grant McKenzie Laws as its youngest member. As is customary, she was at the same time sworn of the Privy Council.

Her husband Sir Jonathan Hugh Mance had become a Lord Justice a year and a half previously, and they are the only married couple both serving on the Court of Appeal. They married in 1973 and were both appointed to the High Court of Justice of England and Wales in 1993, she to the Chancery Division in April and he to the Queen's Bench Division in October.