Andrew Turnbull, Baron Turnbull, is a British politician and civil servant who served as the head of Her Majesty's Civil Service and Cabinet Secretary between 2002 and 2005, when he was succeeded by Sir Gus O'Donnell. He now sits in the House of Lords as a crossbencher.

The Cabinet Secretary is the most senior civil servant in the United Kingdom and is based in the Cabinet Office. The person in this role acts as the senior policy adviser to the Prime Minister and Cabinet, and as the Secretary to the Cabinet is responsible to all ministers for the efficient running of government. The role is currently occupied by Simon Case.