Ain Mere (from birth to Estification Ervin Martson; February 22, 1903 – April 5, 1969) was an Estonian military officer. During World War II, he was an Obersturmbannführer (Lieutenant Colonel) in the Waffen SS and also the head of the Sicherheitspolizei in Estonia (Security Police) following its creation in 1942.
He was born in Vändra and fought voluntarily in the Estonian War of Independence. In early 1919, Mere was wounded while serving on an armored train and was sent to the rear.
According to the KGB archives, he was drafted as an agent of NKVD in 1940–1941. Mere's reports on the resettlement of Baltic Germans and the exposure of underground Estonian organisations reached the desk of Lavrenti Beria. In recognition of his performance Mere was appointed the director of a special department of the Estonian Rifle Corps. He was known under code name "Müller". In July 1941 Mere surrendered himself to the German military. He was a member of the Estonian Security Police (Group B of the Sicherheitspolizei) under the Estonian Self-Administration and participated in the Holocaust.
On February 5, 1945 in Berlin, he founded the Eesti Vabadusliit (anti-communist group) together with SS-Obersturmbannführer Harald Riipalu.
In March 1961, the Soviet court accused during the Holocaust trials in Soviet Estonia the German Security Police in Estonia, headed by Mere (and later by Julius Ennok) to have been actively involved in the arrest and killing of Estonian Jews along with Ralf Gerrets and Jaan Viik. The police were also actively engaged in actions against Estonians deemed to be opponents of the Nazi Germany. Though living in Great Britain, he was sentenced to capital punishment. Great Britain did not extradite him, due to the lack of evidence and he died at the age of 66 in Leicester, England.