Josias Weitbrecht (Russian: Иосия Вейтбрехт, born 6 November 1702 in Schorndorf, died 28 February 1747 in St. Petersburg) was a German professor of medicine and anatomy in Russia.
By the medium of Dr Duvernoy in the year 1721 he came to the University of St. Petersburg, where he studied medicine, physiology and anatomy, his main subject, which he taught students from the academic grammar school, associated with the Russian Academy of Science.
Later, on 22 January 1730, he was appointed ordinary professor of physiology at this university, but in 1743 he underwent the danger to be released despite best credentials due to the expiry of his agreement but until 1746 he could remain in his position with a freelance contract.
Finally due to an intervention of the count Alexei Grigorevich Razumovsky his employment contract could be renewed and Weitbrecht was appointed Full Professor of anatomy in January 1747.
Shortly after having restarted officially his work he suddenly died due to the takings resulting from the above mentioned uncertain situation.