Adam Gottlieb Weigen (1677–1727) was a German pietist, theologian and early animal rights writer.

Biography Weigan was the son of a surgeon and was born at Waiblingen in 1677.Sträter, Udo. (2011). Pietismus und Neuzeit: Ein Jahrbuch Zur Geschichte Des Neueren Protestantismus. Band 36 – 2010. Vandenhoeck & Ruprecht. pp. 120–123. He studied theology at Württemberg but also took interest in anatomy and natural science. Weigen became a pastor and advocate of pietism in Leonberg. He took up this post in 1705. Weigan was influenced by the writings of Philipp Spener.

Weigen argued for a compassionate treatment of the animals from a Christian theological framework.Herberhold, Mechthild; Sölling, Caspar. (2003). Menschenrechte für Menschenaffen?: Was Tier und Mensch unterscheidet. Bonifatius. p. 25. Seidel, Ulrich; Dietrich, Hans-Eberhard. (2019). An der Seite der Tiere: Christsein und ein neuer Umgang mit der Kreatur. Lit. pp. 102–103. In 1711, Weigen authored De Jure Hominis in Creaturas. It has been described as "the first work ever to deal with the topic of animal rights as a general theme."Ingesman, Per. (2016). Religion as an Agent of Change: Crusades – Reformation – Pietism. Brill Publishers. pp. 224–226. The book became known in Denmark and inspired Laurids Smith. It was republished in 2008.

Weigen moved to Wahlheim, where he died in 1727.

Selected publications De Jure Hominis in Creaturas (1711)

References