They're there for a special reason—and not because William Shatner sat there.
Airplanes have their own unique system of cuneiform that passengers may have noticed but never really understood.
The inside of the cabin is marked with little triangles that can be either red or black. An especially astute passenger will notice that these little triangles throughout the cabin line up with the wings outside the plane.
If flight crew need to check the wings, these triangles let them know the best vantage points for the slats and flaps outside. The markings are especially helpful in wintery conditions to make sure the wings are properly de-iced (an inspection required before takeoff, although this is generally done by crew on the ground).
The seats below the triangles can also sometimes be referred to as “William Shatner’s seat.” The phrase is taken from an episode of The Twilight Zone where Shatner sees a goblin out on the wing of his airplane.
There’s also one other hidden perk of these black triangles. If you’re flying an airline that allows you to choose your own seat, look for one of the triangles in the cabin. Anybody who loves taking out-the-window shots or videos for Instagram will get the best view over the wings from these seats.