Alex Jan "Lex" van der Eb (born 16 January 1934) is a Dutch molecular biologist and virologist. He was a professor of fundamental tumor virology and later molecular carcinogenesis at Leiden University from 1979 to 2000. He has performed research in adenoviruses and was fundamental in the creation of the technique of calcium phosphate transfection and the founding of the HEK 293 and PER.C6 cell lines.