Sir Patrick Jeremy Walker, KCB (25 February 1932 – 13 October 2021) was a British civil servant who was Director General (DG) of MI5, the United Kingdom's internal security service, from 1988 to 1992.

[2] The Walkers had once owned considerable lands in northern Nottinghamshire around Mattersey and Lound, but, according to his research, lost it all "thanks to a combination of incompetence and the agricultural slump" at the end of the 19th century.

At the behest of Sir Maurice Oldfield (MI5) and incoming RUC Chief Constable John Hermon, in January 1980 he was asked to review the practices and organisation of intelligence gathering by the Royal Ulster Constabulary in Northern Ireland.

It is claimed by critics that the Walker Report cemented the position of RUC Special Branch as a force within a force, beyond normal checks and balances; established a policy of primacy of intelligence requirements over criminal investigation; led to a perception of informants as an untouchable "protected species"; and to an acceptance of cover-up and fabrication of evidence, such as that revealed after the so-called "shoot-to-kill" killings by police in 1982, that formed the subject of the Stalker inquiry.

[12][13] His term of office saw the statutory basis of MI5 established for the first time through the Security Service Act 1989 and the end of the Cold War.