Aleksis Dreimanis (born August 13, 1914) is an award winning Quaternary geologist. He was born in Riga, Latvia.

He first studied geology at the Institute of Palaeontology at the University of Latvia in Riga. In 1939, he worked as a lecturer at the University. As World War II was being fought, he also took on the responsibility of consulting in Quaternary mapping in the Latvian Institute of Mineral Resources. He was conscripted into the Latvian Legion. After the war Dreimanis was appointed Associate Professor in the Baltic University in the Displaced Persons camps at Hamburg and Pinneberg in Germany.

In 1948, Dreimanis immigrated to Canada to assume a lecturer position at the University of Western Ontario in London, Ontario. Several Canadian institutions called on him for his Quaternary expertise, including the Geological Survey of Canada, the Ontario Department of Mines, and the Ontario Department of Planning and Development for the St. Lawrence Seaway Authority, the Thames River Conservation Authority and various private companies. The university promoted him to Associate Professor in 1956, then to Professor in 1964. In 1980 the university gave made him an Emeritus Professor. In the over 40 years with the university, he has produced over 200 papers, notes and abstracts in the field of Quaternary research.

Between 1974 and 1982, Dreimanis acted as an international advisor for several groups including; the Polish Academy of Sciences, the Geological Survey of Finland, and the Ministry of Education in Finland.

Dreimanis maintained his link with Latvia. He made numerous visits as an invited lecturer to Riga, and to Tallinn in Estonia. He was a correspondent with the Dictionary of Latvian Technical Terminology from 1970 to 1986. He has been an associate editor of the Technical Review Journal (for Geology) from 1979. He served as s Chairman of the Commission on Technical and Natural Sciences at the Latvian Cultural Foundation from 1973 to 1976.