Dame Barbara Jean Lyon Mills DBE, QC (née Warnock; 10 August 1940 – 28 May 2011) was a British barrister.

[2] She was educated at St. Helen's School, Northwood, where she became head girl, and then studied law at Lady Margaret Hall, Oxford, graduating in the second class in 1962.

She was Director of the Serious Fraud Office (SFO) from 1990 to 1992, during investigations of Barlow Clowes, Blue Arrow, Robert Maxwell's Mirror Group, and Polly Peck.

[2] During that period, the SFO was investigating a company set up by her brother-in-law David Mills, then husband of Labour cabinet minister Tessa Jowell, in connection with bribery allegations against Silvio Berlusconi, but declined to investigate Mills himself.

[5] David Mills was later found guilty of accepting a cash bribe from Berlusconi, but the conviction was quashed by Italy's Supreme Court of Cassation.

She resigned in 1998 after she was criticised in reports by Gerald Butler and Sir Iain Glidewell for repeatedly refusing to bring prosecutions over deaths in police custody.

On 1 June 2016 the Coroner re-opened the inquests after a 42-year adjournment a decision opposed by West Midlands Police.

[8][11] Mills retained the role as Adjudicator for HM Revenue and Customs when those bodies were merged in 2005, and held this post until 2009.