Are aliens real?
Whether aliens are real or not--and whether there is evidence to prove whether they are real or not--depends upon whom you talk to. If you talk to the average citizen around the world, you will (usually) be told that, no, they are not real and, no, there is no evidence proving they are real [there is also no evidence, except experiential evidence (what an individual sees or hears), proving they are not real]. If you talk to conspiracy theorists interested in government cover-ups of alien visitations, you will be told they are real and will be shown piles of visual evidence proving they are real.
If you talk to individuals who have had first-hand experience with observing what is described (by them) as alien space craft, or unidentified flying objects, you will be told aliens are real, and their personal visual experience(s) proves they are real.
Former President Jimmy Carter is one who has seen unexplained lights (1969) and states that, as a scientist and amateur astronomer, he knows what he saw was no astronomical phenomenon and no known military craft (perhaps, though, an experimental, silent military aircraft from a near-by base). Carter filed a belated report in 1973 with the National Investigations Committee on Aerial Phenomena detailing his 1969 sighting.
If you talk to certain retired NASA astronauts, like moon-walker Edgar Mitchell of Apollo 14; certain former government officials, like Paul Hellyer, Canadian Defense Minister during the 1960s; certain commercial and military aircraft pilots, like former Air Force Maj. George Filer, you will be told that aliens are real and that there is a substantial body of evidence, including first-hand visual and radar sightings and trackings, proving they are real.
There is a continually growing movement among commercial and military pilots, NASA personnel and officials, and government officials that hopes to encourage average citizens to compel governments across the world to be forthright and forthcoming about what witnesses attest to be the presence of aliens on Earth, in the skies above Earth and--faithfully asserted, even if surprising--on the Moon and in near-space between Earth and the Moon. Consequently, the answer you receive to "Are aliens real?" depends entirely upon whom you ask. And when asking, you will be challenged to weigh the credentials, experience and credibility of the one answering.
The term 'alien' refers to a life form of extra-terrestrial origin, that is, an organism that does not belong to our Earth. There are a number of conspiracy theories regarding the presence of aliens among us, including the Roswell conspiracy, Area 51, etc. These have been aided (to some extent) by movies based on alien life forms. There is little scientific evidence to support such claims and no government (around the globe) has supported such assertions. Among the scientific community and enthusiasts, SETI (search for extraterrestrial intelligence) program is attempting to find the presence of intelligent life forms in the universe. The first step in such a direction is to find Earth-like planets, that can support life. Another approach is to look for any radio signatures, waves, etc. (anything out of ordinary in the space) to relate it to intelligent life elsewhere. Till date, there is no confirmed evidence of the presence of aliens.
Hope this helps.