Wendelle C. Stevens (1923–2010) was an American Air Force officer turned ufologist, best known as the leading American promoter of the Swiss contactee Billy Meier and as a collector and publisher of UFO photographs and contact stories. Working from Tucson, Arizona, he wrote, co-wrote or translated a long shelf of books on people who said they had met extraterrestrials, and he said he held the world's largest private collection of UFO photographs.

Stevens was born on January 18, 1923, in Round Prairie, Minnesota. After high school he enlisted in the Army, later earned a commission in the Army Air Corps and stayed on in the postwar Air Force. His interest in UFOs began, he said, while he was serving in Alaska, and after retiring from the Air Force in 1962 as a lieutenant colonel he devoted himself to the subject. He wrote often for UFO magazines and appeared in documentaries of the period, among them UFOs Are Real (1979).

Meier became the center of his work. Stevens persuaded the investigator Lee Elders to look into the case, spent close to three months with Meier in Switzerland and maintained that Meier's photographs were unmanipulated pictures of a real alien craft; he even said Meier had been taken by the aliens a few feet away while Stevens's back was turned. His UFO Contact from the Pleiades reports and the 1987 documentary Contact, in which he appeared, presented the case to American audiences. He also published UFO Contact from Reticulum (1981) with William J. Herrmann, recounting Herrmann's claimed sightings and abductions around Charleston, South Carolina, and later produced an English translation of UFO Contact from Andromeda, a diary attributed to a scientist named R. N. Hernandez.

In 1982 Stevens was arrested in Tucson on child molestation charges. According to a 1987 report in Spin magazine, he pleaded guilty to nine of the charges under a plea agreement and was sentenced to seven years in prison; he was paroled in 1988 and returned to UFO research. Stevens and some supporters later claimed that he had been framed by the CIA.

Stevens passed away in Tucson in 2010. His archive was later broken up and sold online; the curator Gordon MacDonald tracked it down and exhibited slides from it at The Photographers' Gallery in London in 2017. In 2023 the Archives of the Impossible at Rice University, founded by Jeffrey Kripal, accessioned a Wendelle C. Stevens collection. Images credited to his archive, including Meier photographs, circulated online in 2026, and his books, from the Reticulum case to the Andromeda diary, remain much of the English-language record of the contact claims he championed.