Lembit Öpik (born March 2, 1965) is a Liberal Democrat politician in the United Kingdom. He is member of Parliament for Montgomeryshire, and is Lib Dem shadow Secretary of State for Wales and Northern Ireland.

He has announced that he will be a candidate in the forthcoming internal election for the position of President of the Liberal Democrats. The party president chairs a number of party committees and is also a figurehead who represents the party at official functions. Simon Hughes is also a candidate for the position of party president.

His parents were refugees from Estonia, and he entered Parliament at the 1997 election. He was President of University of Bristol Union, and was on the National Union of Students executive.

To the general public he is perhaps best known for his concerns about the possibility of an asteroid impact on Earth, and his advocacy for increased funding for attempts at detection, under the banner Spaceguard. His grandfather was Ernst Julius Öpik, an Estonian astronomer.

He has appeared several times on Have I Got News For You.

He is engaged to to ITV weather forecaster Sian Lloyd.