Serghei Nicolau

Serghei Nicolau (born Sergey Nikonov; 1905–1999) was a Romanian communist espionage chief.

An ethnic Russian, Nicolau, like his boss Emil Bodnăraș, was recruited by the NKVD. This occurred in the late 1930s after he was expelled from the Chemistry faculty of Iași University, for attending meetings of the banned Romanian Communist Party (PCR). His studies abroad, in Brussels and Marseille, were paid for, and in the latter city, he was part of the local French Communist Party leadership. At the beginning of World War II, he was assigned to return to Romania in order to set up a spy network, but he was captured at sent to prison, where he spent part of his sentence alongside another NKVD agent, Gheorghe Pintilie. While at Doftana prison, the two belonged to a group of Soviet agents around future PCR leader Gheorghe Gheorghiu-Dej. Following the 1949 arrest of N. D. Stănescu, he was made head of the External Intelligence Service (SSI). Guided by Bodnăraș, he worked to recruit loyal agents, both within the agency and in the Romanian Army. In consultation with the local Soviet espionage bureau, the pair reorganized the SSI into four bureaus: foreign information, supervision of diplomatic missions in Bucharest, domestic information and counterespionage activities. From 1954 until his retirement in 1960, Nicolau, who held the rank of lieutenant-general, led the military espionage bureau of the Romanian General Staff.

In the early 1950s, his wife Nina was Gheorgiu-Dej's personal secretary.