Ken-Marti Vaher (5 September 1974) is a leading member of the Estonian Res Publica party, and the former Minister of Justice .

Vaher, born in Tallinn in 1974, was educated at the University of Tartu, where he received a bachelors degree in law. A carrier politician and civil servant Vaher served as Director of the State Audit Office as well as a member of the Tallinn City Council, before being appointed to the Minister of Justice position in the Juhan Parts government.

On 21 March 2005, Vaher received a vote of no confidence from the Riigikogu. The vote followed concerns about the handling of a controversial anti-corruption plan. The plan, as it was proposed, would have established a quota system of how many civil servants had to be prosecuted every year, it was set on a per county basis. Members of the opposition in the Riigikogu considered the programme as draconian. On 24 March, Prime Minister Juhan Parts announced that he would step down from the position of Prime Minister and request that the President reform the government, in part having to do with Part's support for the program.