William Henry Smyth (January 21, 1788 - September 8, 1865) was a British hydrographer, Royal Navy officer, numismatist, and astronomer. Born in London, Smyth ran away from home at fourteen and became a cabin boy on a merchant ship. When the ship was commandeered by the Royal Navy, Smyth began his naval career as an ordinary seaman. He served with distinction during the Napoleonic Wars (1803 - 1815), spending from 1804 through 1808 in the Pacific and in the waters off India, China, and Australia. From 1809 through 1815 he served in Europe, participating in the defense of Cadiz and the defense of Sicily. He was promoted to lieutenant on March 25, 1813, and then to Commander on September 18, 1815. With this promotion he was placed in command of the brig Scylla which he used to continue the hydrographic survey work and his surveys off the coast of Sicily, along with the adjacent shorts of Italy, and the North African coast. He transferred to the Aid in 1817 and continued his survey work along the Italian, Sicilian, Greek, and African coasts. These surveys resulted in the creation of numerous charts, which were used by the Royal Navy until the mid-20th century. He met the astronomer Giuseppe Piazzi in Palermo in 1817 and visited his observatory, which sparked an interest in astronomy. He was promoted to Post-Captain in 1824, which ended his service at sea with the Royal Navy. He settled in Bedford, England, in 1825, and established his own private observatory. From here he observed nebulae, star clusters, and double stars, leading him to publish Cycle of Celestial Objects in 1844. This book earned him the Gold Medal of the Royal Astronomical Society in 1845 and the presidency of the society. He retired from the Navy in 1846 on half-pay, and was promoted to Rear-Admiral, Vice-Admiral, and finally Admiral on November 14, 1863. He was awarded the Royal Geographical Society's Founder's Medal in 1854 for his survey work in the Mediterranean.