Helwig Dieterich Latinized as Helvicus Dietericus (24 June 1601 – 13 December 1655) was a German physician and chemist.
He served as a physician to several members of royalty and nobility but earned notoriety after several of his cures were questionable and proved deadly.
Otto Tachenius wrote an Apologia in 1652 in which he declared Dieterich as a pseudo-chimicum (false chemist) and a fraud.
Dieterich was born in Kyrtorf in Hesse-Darmstadt, son of the priest and theologian Johannes (1572–1635) and Barbara Reichard.
He travelled in Italy around 1625 and worked at Rüeber's Apotheke zum Löwen in Ulm with studies under the physician Sebastian Stromeier.