Thinkers of the Ancient era thought about the possibility of the existence of other worlds in the Universe, inhabited by intelligent beings. Nowadays, astronomers in many countries are trying to establish contacts with extraterrestrial civilizations, but so far, alas, without success. At the same time, in the folklore of various nations, aliens from the sky appear, most of them strange-looking creatures, but kind and smart, teaching earthlings various worldly wisdom . Ancient and modern images of such aliens are known, as well as records of events that do not fit into the framework of common sense, but become logical and understandable if we assume the participation of aliens in them. Moreover, there are thousands of reports of meetings between people and aliens, which left indisputable evidence their reality. All this is described in this book, designed for the widest range of curious and unbiased readers.