William, Duke of Brunswick-Wolfenbüttel (1806-1884) was the ruling duke of the Duchy of Brunswick from 1830 until his death. He was the son of Frederick William, Duke of Brunswick-Lüneburg and Princess Marie of Baden. Upon the death of his father, King George IV became his guardian. His death caused a constitutional crisis for Brunswick lasting until the accession to the dukedom of Ernest Augustus, the son of the Duke of Cumberland, in 1913. William did not marry, but had a number of illegitimate children.

The Duke appears here head and shoulders, dressed in an Austrian General's uniform with a tall, peaked cap; he wears the star of the Order of Henry the Lion, encircled with the Garter; he has blue eyes, and a thick beard and moustache.