Sir Augustus Frederick d'Este, KCH (13 January 1794 – 28 December 1848) was a relative of the British royal family and the earliest recorded person for whom a definite diagnosis of multiple sclerosis can be made.

D'Este was the son of Prince Augustus Frederick, Duke of Sussex, and Lady Augusta Murray, and a grandson of King George III.

After the birth of their first child, the marriage was discovered by the King and formally annulled, making their son illegitimate in Great Britain.

Augustus d'Este is the earliest recorded person for whom a definite diagnosis of multiple sclerosis can be made.

During the course of his disease he developed weakness of the legs, clumsiness of the hands, numbness, dizziness, bladder disturbances, and erectile dysfunction.