Augustus II (10 April 1579 – 17 September 1666), called the Younger (German: August der Jüngere), a member of the House of Welf was Duke of Brunswick-Lüneburg.

Considered one of the most literate princes of his time, he is known for founding the Herzog August Library at his Wolfenbüttel residence, then the largest collection of books and manuscripts north of the Alps.

Ten years later, however, upon his marriage with Ursula, a daughter of the Ascanian duke Francis I of Saxe-Lauenburg, he had to waive all rights and claims and was compensated with the small Dannenberg lordship.

After lengthy and complicated negotiations with his reluctant Welf relatives and an intervention by Emperor Ferdinand II, it was finally agreed that Augustus should inherit the Wolfenbüttel principality.

[3] The duke employed the scholar Justus Georg Schottel as tutor of his sons; he also kept an active correspondence with Johannes Valentinus Andreae, a founder of the esoteric Rosicrucianism movement.