Sten Yngve Dennis Lagergren (6 May 1876 – 4 April 1922) was a Swedish physical chemist known for his fundamental findings in adsorption kinetics. Lagergrens's 1898 article "Zur Theorie der Sogenannten Adsorption Gelöster Stoffe" (To the theory of the so-called adsorption of dissolved materials) brought him a lasting fame. In 2018, 120 years after its publication, the paper was cited more than 800 times according to Clarivate Analytics' Web of Science, making its total number of citation above 6000. In addition, his name became an eponym in the form of Lagergren equation or Lagergren kinetics occurring several thousand times in the literature.