Tadeusz Jaczewski (February 1 1899, Saint Petersburg – February 25 1974) was a Polish entomologist who specialised in Hemiptera.
Jaczewski studied at the Saint Petersburg State University, then taught at the University of Warsaw. He also worked for the Warsaw Zoological Museum.He published many papers on the insect fauna of Poland and with I.M Kerzhner 1964 wrote Order Hemiptera (Heteroptera). In Bei-Bienko, G. Ya. (ed.), Keys to the insects of the European USSR 1: 655-845 1964.He was a specialist in Nepomorpha