An aide-de-camp (French: camp assistant) is a personal assistant, secretary, or adjutant to a person of high rank, usually a senior military officer or a head of state. The first aide-de-camp is the foremost personal aide.

In some countries, aide-de-camp is considered to be a title of honour (which infers the post-nominal letters ADC), and participates at ceremonial functions. For example, Prince Andrew, Duke of York of the British Royal Family is currently the aide-de-camp to his mother, Queen Elizabeth II. Similarly, Geraud Duroc was made an aide-de-camp to Napoleon in 1796, and first aide-de-camp in 1798.

The badge of office for an aide-de-camp is the aiguillette, a braided cord in gold or other colours, worn with a uniform on the left (or sometimes right) shoulder.