The empennage ( /ˌɑːmpɨˈnɑːʒ/ or /ˈɛmpɨnɪdʒ/), also known as the tail or tail assembly, of most aircraft gives stability to the aircraft, in a similar way to the feathers on an arrow. Most aircraft feature empennage incorporating vertical and horizontal stabilising surfaces which stabilise the flight dynamics of pitch and yaw, as well as housing control surfaces.

In spite of effective control surfaces, many early aircraft that lacked stabilising empennage were virtually unflyable. Today, only a few (often relatively unstable) heavier than air aircraft are able to fly without empennage ("tailess").

Structurally, the empennage consists of the entire tail assembly, including the fin, the tailplane and the part of the fuselage to which these are attached. On an airliner this would be all the flying and control surfaces behind the rear pressure bulkhead.

The front, usually fixed section of the tailplane is called the horizontal stabilizer and is used to balance and share lifting loads of the mainplane dependent on centre of gravity considerations by limiting oscillations in pitch. The rear section is called the elevator and is usually hinged to the horizontal stabilizer. The elevator is a movable airfoil that controls changes in pitch, the up-and-down motion of the aircraft's nose. Some aircraft employ an all-moving stabilizer and elevators in one unit, known as a stabilator.