Dorothy Ruth Bain KC is a Scottish advocate who has served as Lord Advocate since 2021. She is the second woman to hold the office after Lady Elish Angiolini KC. Bain previously served as the Principal Advocate Depute from 2009 to 2011, the first woman to hold the prosecutorial position in Scotland.

Born in Edinburgh, Bain attended the University of Aberdeen School of Law, graduating with an LLB and a Diploma in Legal Practice. In 1994, she became an advocate and in 2007 she was appointed Queen's Counsel, now King's Counsel. Bain served as an Advocate Depute in the Crown Office from 2002 to 2011 and was appointed the first female Principal Advocate Depute from 2009 to 2011. In 2008, she was commissioned to report on the prosecution of sex crimes in Scotland, the outcome of which led to the formation of Scotland's National Sex Crimes Unit in 2009. She returned to private practice in 2011.

First Minister Nicola Sturgeon nominated Bain for Lord Advocate and on 22 June 2021 she was sworn into office at the Court of Session with Ruth Charteris KC, Solicitor General. It is the first time both positions have been held by women at the same time. In October 2022, she argued the Scottish Government's unsuccessful case in the UK Supreme Court on the legality of a second referendum on Scottish independence.

One of five children, Bain's mother was a shorthand typist and her father was a postman. She attended the University of Aberdeen, where her older sister, Helen, was studying medicine and then her younger sister, Elizabeth, studied psychology. They were the first generation in her family to attend university. She earned an LLB degree and a Diploma in Legal Practice.

Completing her traineeship with TF Reid & Donaldson, a law firm in Paisley, Bain was still unsure of where she wanted to take her legal career. After working for Dundas & Wilson, she began her career as an advocate in 1994. She worked in civil practice from 1994 until 2002.

From 2002 to 2011 she served as an Advocate Depute working within the Crown Office and Procurator Fiscal Service. In 2008, she was commissioned by the Lord Advocate, Elish Angiolini, and the Solicitor General, Frank Muholland, to report on and make recommendations on the prosecution of sex crimes in Scotland, the outcome of which led to the formation of Scotland's National Sexual Crimes Unit.

In June 2009, Bain became the first and highest-ranking female to hold the prosecutorial position in Scotland, as Principal Advocate Depute. She became known for her prosecution of high-profile cases such as the serial killer Peter Tobin, the Operation Algebra case which resulted in the conviction of (then) the largest paedophile ring in the UK, as well the prosecution of four members of a drug gang for murder, and a wide-ranging 2009 child pornography case.

Bain has been instructed in cases at all levels, including the Court of Session, Court of Criminal Appeal, High Court of Justiciary, Supreme Court of the United Kingdom, and the European Court of Human Rights.