A T-tail is an empennage configuration in which the tailplane is mounted to the top of the fin. The arrangement looks like the capital letter T, hence the name. The T-tail differs from the standard configuration in which the tailplane is mounted to the fuselage at the base of the fin.
Avro RJ-85 of SN Brussels Airlines (Belgium)
McDonnell Douglas MD-90
Piper PA-44-180 Seminole
Grob G 109 motor glider
The empennage, also known as the tail or tail assembly, is a structure at the rear of an aircraft that provides stability during flight, in a way similar to the feathers on an arrow. The term derives from the French language verb empenner which means "to feather an arrow". Most aircraft feature an empennage incorporating vertical and horizontal stabilising surfaces which stabilise the flight dynamics of yaw and pitch, as well as housing control surfaces.
The empennage of an Atlas Air Boeing 747-200
SpaceShipOne at the US National Air and Space Museum
The DH108 Swallow