Mark N. Dion (born 1955) is an American politician, law enforcement officer and lawyer from Maine, who has served as Mayor of Portland since December 4, 2023.

Dion was criticized during his 2002 campaign for using a county credit card and attending law school.

Rather than seek re-election as sheriff, he successfully sought a seat in the Maine House of Representatives.

[3] In March 2015, while a member of the House, Dion announced that he would sponsor legislation to make marijuana legal.

[8] During his campaign, he promised to continue supporting a policy of forcibly removing homeless people from public spaces, stating “The sweeps will continue.” Incumbent mayor Kate Snyder, herself the former Executive Director of the Maine Department of Corrections, endorsed Dion.