An aide-de-camp (English: /ˌeɪd dɪ ˈkæmp/ /-ˈkɒmp/; French: [ɛd də kɑ̃]; plural: aides-de-camp) is a personal assistant or secretary to a person of high rank, usually a senior military, police or government officer, or to a member of a royal family or a head of state. The term comes from a French expression meaning "helper in the military camp".

An aide-de-camp may participate at ceremonial functions, and the first aide-de-camp is typically the foremost personal aide. This is not to be confused with an adjutant, who is the senior administrator of a military unit.

The badge of office for an aide-de-camp is usually the aiguillette, a braided cord in gold or other colours, worn on the shoulder of a uniform. Whether it is worn on the left or the right shoulder is dictated by protocol.

In some countries, aide-de-camp is considered to be a title of honour, which confers the post-nominal letters ADC or A de C.