Danielius Segalis (1915–?) was born in Jonava. In 1934, he graduated from Juozas Tumas Vaižgantas Gymnasium in Rokiškis and entered the Pharmacy Department at the Faculty of Medicine of Vytautas Magnus University. In 1935, he had to abandon his studies due to compulsory military service. On 5 July 1938, Segalis enrolled in the Chemistry Department at the Faculty of Mathematics and Natural Sciences of Vytautas Magnus University. That same year, he transferred to the Chemistry Department at the Faculty of Mathematics and Natural Sciences of Vilnius University. On 19 September 1941, Segalis was expelled from the university by the Order of 17 September 1941 of the Department of Higher Education under the Board of Education, which was subordinate to the National Socialists. No further information on his fate is known.