Alexandra Louise Mayer (born 2 June 1981) is a British Labour Party politician who has served as the Member of Parliament (MP) for Dunstable and Leighton Buzzard since 2024.

In the 2014 European Parliament election she stood in for the East of England region in second position on the Labour list,[5] which did not yield a seat, but took over from Richard Howitt following his resignation.

In the European Parliament she was Labour's spokesperson for the foreign affairs (16–18) and the economy (18–19)[4] and a member of the US-EU Relations Delegation.

[9] In May 2024, Mayer was selected to be Labour's candidate for the new constituency of Dunstable and Leighton Buzzard at the 2024 general election.

[10][11] On 4 July 2024, Mayer won the Dunstable and Leighton Buzzard seat from the Conservatives by a margin of 667 votes (1.4%), becoming the area's first female MP.