Charles Augustin Busby (27 June 1786 – 18 September 1834) was an English architect.

He created many buildings in and around Brighton, Sussex, such as Brunswick Square and St Margaret's Church. His style usually included Romanesque-style pillars to his buildings.

He entered into an architectural partnership with fellow architect Amon Henry Wilds and his apprentice David J. Field. This has been called a decisive movement in his career. It was a partnership suggested by Thomas Read Kemp who was developing property in Brighton. Busby became key in the development of Brighton, not just as an architect but also investing in development himself.

Busby was born in London on 27 June 1786. He was the eldest of seven children born to the composer, musician and author Thomas Busby and Priscilla (née Angier). His parents socialised with people such as William Blake, Byron, Merlin the Ingenius Mechanic, Henry Vassal-Fox, 3rd Baron Holland and his wife Elizabeth Fox, Baroness Holland. It is said that they were politically radical.

In 1811 he married Louisa Mary Williams, with whom he had two children.

He was educated by his parents and shared his father's interest in science. Around 1802, when he was 16, he started a pupillage with the civil engineer and architect Daniel Asher Alexander.

Under the recommendation of Alexander that Busby entered the Royal Academy School in 1803. He graduated in 1807 and in 1808 was awarded the Gold Medal of the Royal Academy for an architectural drawing of proposed premises for the Royal Society and the Society of Antiquaries.

In 1808 Busby published his first book called 'A Series of Designs for Villas and Country Houses adapted with Economy to the Comforts and to the Elegancies of Modern Life. In the preface to this book Busby attacked the fashion for Egyptian architecture: "Of all the vanities which a sickly fashion has produced, the Egyptian style in modern Archi-tecture appears the most absurd". He preferred the simplicity of Greek architecture.