Prince Octavius (23 February 1779 – 3 May 1783) was the thirteenth child and eighth son of King George III and his queen consort, Charlotte of Mecklenburg-Strelitz. Six months after the death of his brother Prince Alfred, Octavius was inoculated with the smallpox virus. Several days later, he became ill. His subsequent death at the age of four devastated his parents, and in particular his father. King George III was very fond of his two youngest sons, Alfred and Octavius, and his later bouts of madness would involve hallucinations of his dead sons. The king's eldest son, George IV, later served as regent for his mentally ill father.