Mark Lamb (born July 14, 1972) is an American law enforcement officer and politician who has served as sheriff of Pinal County, Arizona, from January 1, 2017 until December 31, 2024.

[6] In November 2019, Lamb called for increased security along the Mexico–United States border to combat drug cartels from harming U.S. National Parks.

In June 2020, he tested positive for COVID-19 a week before his scheduled appearance at the White House for Donald Trump's signing of executive order 13925.

[3] In July 2020, in response to the protests following the murder of George Floyd, Lamb announced his intention to form a civilian posse of non-felon volunteers with four hours of training in legal guidelines and basic police tactics.

[10] In 2020, Lamb spoke at a convention of the Constitutional Sheriffs and Peace Officers Association, an organization that holds the fringe legal theory[11] that sheriffs are the supreme legal authority in the United States and are not required to enforce laws they believe to be unconstitutional.

Lamb ran unopposed for re-election in November 2020 after successfully suing to remove his competition from the ballot.

[13] In April 2023, Lamb announced he would run for the seat currently held by incumbent Democrat-turned Independent Kyrsten Sinema.

[6] On December 16, 2022, Lamb's son, Cooper, daughter-in-law, and infant granddaughter died in a traffic collision in Gilbert, Arizona.