"Ancient Aliens"   The alien show to end all alien shows, this History Channel classic has been on the air since 2009 and is still going strong. In that time, it's produced 157 episodes and birthed a well-known meme  -- a wild-haired and slightly orange Giorgio A. Tsoukalos throwing up his hands during his passionate explanation of an extraterrestrial theory.

"In Search of Aliens"  If you're a fan of Giorgio Tsoukalos, there's more of him where "Ancient Aliens" came from. The Swiss television personality, producer, and self-proclaimed "Ancient Astronaut theorist" believes that ancient alien astronauts may have interacted with ancient humans. This is Tsoukalos' own personal show, and in it, he travels the world pondering oft-considered myths like Bigfoot and the lost city of Atlantis, searching for proof of aliens. It aired on History for only one season in 2014, but you can still watch full episodes for free online through History, or via Amazon Prime Video.

"Project Blue Book"   This Robert Zemeckis-produced, fact-based scripted drama series premiered this past winter on History Channel, and has already been renewed for a second season. Inspired by the personal experiences of Dr. J. Allen Hynek (played by “Game of Thrones” alum Aidan Gillen), the series delves into the top-secret military investigations into UFOs and related phenomena in the 1950s and 60s.

"Unidentified: Inside America's UFO Investigation"   As if History didn't already dominate the alien space, they came in hot with a new series this year executive produced by Tom DeLonge of pop-punk band Blink-182. The series boasts new evidence, footage and eyewitness interviews about a once-hidden government organization devoted to investigating UFOs.

"UFOs: The Lost Evidence"    Hey, Travel Channel likes aliens too! This series has been airing since 2017, with new episodes currently  emerging weekly. This season, each episode features new audio, video and documentary evidence of extraterrestrial contact from government officials, the military and police, scientists and professors, plus eyewitness encounters. A new episode airs on Travel Channel July 14.

"Alien Highway"   From Travel Channel, this new series debuts July 17 featuring Chuck Zukowski, a former Colorado law enforcement officer, who's been researching and investigating UFO-related incidents for over 30 years. "Now, together with his son Daniel and investigator Heather Taddy, he is pursuing the cases that authorities ignore, finding evidence that others have missed, listening to witnesses that are otherwise afraid to come forward, searching for definitive proof of UFOs along America's Alien Highway," according to Travel Channel's description.

"UFOs: The Best Evidence Ever Caught on Tape"   Throwback to the year 2000, when for one season and one season only, Jonathan Frakes, who played Riker on "Star Trek: The Next Generation," narrated a show about amateur UFO footage.  Luckily, it's streaming on Netflix. 

"UFO Hunters"   Another History Channel series, this one features interviews with witnesses who've reported UFO encounters, and sticks close to the facts. It aired for 3 seasons from 2008 to 2009, but you can still watch episodes on History's website.

"Unsealed: Alien Files" This one has all the hallmarks of a good conspiracy program: Dramatic, rumbling voice overs, 3D alien graphics of every color and historic conjecture that surmises whether the founding fathers might have actually known about aliens the whole time. The series originally aired on History in 2012, but it's currently available to stream on Netflix.

"UFOs Declassified"   This Canadian TV series aired for one season in 2015 on History Canada. Starring Brad Cartner, the series and looks into the correlation between UFO sightings nuclear facilities.