KIC 8462852 is an F-type star with an unusual light oscillations discovered by the Planet Hunters project. This is the only known star with small, frequent, non-periodic dips in brightness.
These observations could not be explained by intrinsic variability of the star itself, they point to many objects of small mass that orbiting the star. One of possible explanations is that these objects could be parts of a megastructure made by an extraterrestrial civilization. However, this also can be explained by the planetary or comet debris around the star.