Theodor Escherich (German pronunciation: [ˈteːodoːɐ̯ ˈʔɛʃəʁɪç]; 29 November 1857 – 15 February 1911) was a German-Austrian pediatrician and a professor at universities in Graz and Vienna.

Later, he finished secondary education in Würzburg, where he attended a Gymnasium (classical language high school) and took his Abitur examination in 1876.

In the following two years, he attended lectures in Vienna (with Hermann von Widerhofer and Alois Monti) and did bacteriological research work at the St Anna Children's Clinic.

This work, presented to the medical faculty in Munich and published in Stuttgart, Die Darmbakterien des Säuglings und ihre Beziehungen zur Physiologie der Verdauung (1886) (Enterobacteria of infants and their relation to digestion physiology), was to become his habilitation treatise and established him as the leading bacteriologist in the field of paediatrics.

In 1902, Escherich succeeded Hermann Widerhofer as full professor of pediatrics in Vienna, where he directed the St.-Anna-Kinderspital (St. Anna Children's Hospital).