There's the vertical stablizer, which is the "tail fin" of the plane. This keeps the plane in line with the direction of motion. In other words, it controls yaw. To change yaw, a pilot moves the rudder, also found on the tail. (How Things Fly)

This is why we adorn the tails of our aircraft with personalities who have pushed boundaries. Today, we have tail fin heroes from several of the countries we operate in, including all the Nordic countries, as well as Spain, France, England, Ireland and Scotland. (Norwegian)

Nothing evokes wanderlust quite like an aeroplane tail fin. Fun and colourful or corporate and business like, they’re graphic representations of both the airline and the countries they represent... (wanderlust)