For decades, the United States federal government has been the ultimate focal point for lore, speculation, and institutional distrust. While real-world history contains plenty of verified covert programs, the intersection of government secrecy with the unknown has birthed a sprawling mythology. Conspiracy theorists and folklore enthusiasts have long accused Washington of hiding things that defy standard science—ranging from crashed extraterrestrial ships and biological entities to suppressed prehistoric anomalies and supernatural forces.

Here is a look at ten of the most prominent conspiracy theories alleging that the U.S. federal government has covered up fossils, extraterrestrial life (EBEs), and other high-strangeness phenomena.

1. The Roswell UFO Crash and Military Cover-Up (1947)

• The Claim: In July 1947, a mysterious craft crashed onto a ranch near Roswell, New Mexico. While the military initially issued a headline-grabbing press release stating they had recovered a “flying disc,” they quickly retracted it, claiming it was merely a routine weather balloon.
• The Conspiracy: Generations of theorists maintain that an actual extraterrestrial spacecraft—along with its non-human crew—was recovered and whisked away to a secure military installation. The “weather balloon” narrative is viewed as the foundational cover-up story of modern ufology. (Later Air Force reports attributed the debris to Project Mogul, a top-secret acoustic surveillance balloon project tracking Soviet nuclear tests, doing little to quell believers).

2. Area 51 and the Reverse-Engineering of Alien Tech

• The Claim: Groom Lake, a heavily classified remote detachment of Edwards Air Force Base in Southern Nevada (famously known as Area 51), is surrounded by the strictest restricted airspace in the country.
• The Conspiracy: Because the federal government kept the base’s existence shrouded in secrecy for decades (the CIA only formally acknowledged it in 2013), it became the ultimate rumored hub for extraterrestrial containment. Theorists claim that underground facilities beneath the desert floor house living and dead Extraterrestrial Biological Entities (EBEs) alongside captured flying saucers being reverse-engineered by government scientists.

3. The Smithsonian’s Alleged Suppression of Giant Skeletons

• The Claim: Throughout the late 19th and early 20th centuries, American newspapers frequently published sensational accounts of archaeologists unearthing anomalous, exceptionally tall skeletons (often 7 to 10 feet tall) with double rows of teeth or unusual cranial structures in ancient burial mounds across the Midwest.
• The Conspiracy: A persistent fringe theory claims that the Smithsonian Institution and other federal agencies systematically confiscated, hid, or destroyed these “giant” skeletal remains. Believers argue the government acted to protect conventional, officially sanctioned timelines of human evolution and North American history, covering up a forgotten race of prehistoric giants.

4. Majestic 12 (MJ-12) and the Secret Government Shadow Cabinet

• The Claim: In the 1980s, leaked documents surfaced detailing the existence of “Majestic 12,” a purported secret committee of top-tier scientists, military leaders, and government officials allegedly formed by President Harry S. Truman in 1947.
• The Conspiracy: According to the documents, MJ-12 was tasked with recovering, studying, and concealing crashed extraterrestrial technology and managing contact with non-human intelligence. While mainstream historians and researchers have widely debunked the documents as elaborate hoaxes, the concept of a shadow executive committee running unauthorized supernatural research remains a staple of deep-state lore.

5. The Philadelphia Experiment and Sub-Atomic Cloaking (1943)

• The Claim: During World War II, the U.S. Navy allegedly attempted to apply Albert Einstein’s Unified Field Theory to a naval destroyer, the USS Eldridge, docked in the Philadelphia Naval Shipyard.
• The Conspiracy: Lore dictates that the experiment went catastrophically wrong, rendering the ship entirely invisible, teleporting it to Norfolk, Virginia, and back, and leaving surviving crew members fused into the metal bulkheads or driven completely insane. Theorists claim the federal government suppressed the entire incident to prevent mass panic and hide the discovery of accidental interdimensional gateway technology.

6. The Dulce Base and Underground Extraterrestrial/Human Conflict

• The Claim: Located deep beneath the remote Archuleta Mesa on the border of New Mexico and Colorado, Dulce is rumored to house a massive, multi-level subterranean laboratory.
• The Conspiracy: Popularized by fringe whistleblowers in the late 20th century, the legend claims that the U.S. government entered a secret treaty with subterranean grey aliens, trading human and animal test subjects for advanced extraterrestrial technology. The conspiracy peaks with stories of an armed conflict (the “Dulce Wars”) between human military personnel and alien entities deep underground.

7. The Stargate Project and Weaponized Remote Viewing

• The Claim: During the Cold War, the U.S. Army and the CIA did indeed fund paranormal research initiatives (such as Project Stargate at Fort Meade) to investigate the viability of psychic phenomena for military intelligence.
• The Conspiracy: While the government eventually declassified and canceled these programs in the 1990s after concluding they lacked actionable reliability, hardcore theorists believe the military never truly stopped. The ongoing cover-up narrative suggests that deep-black projects continue to successfully train “remote viewers” to spy on foreign installations, astral-project into alternate dimensions, and track supernatural anomalies.

8. Hangar 18 at Wright-Patterson Air Force Base

• The Claim: Long before Area 51 dominated popular culture, Wright-Patterson Air Force Base in Dayton, Ohio, was considered the primary historical repository for recovered military wreckage.
• The Conspiracy: Conspiracy culture links Hangar 18 directly to the aftermath of the Roswell crash, alleging that debris, disabled saucers, and deceased alien bodies were quietly flown there for autopsy and scientific analysis. Despite repeated military denials and a lack of verifiable evidence, the base remains synonymous with hidden government trophy rooms.

9. The Suppression of Alternative Free Energy and Suppressed Tech

• The Claim: Innovators throughout history—most famously Nikola Tesla—developed technologies capable of harnessing boundless, zero-point, or anti-gravity energy derived from the natural electromagnetic fabric of the Earth and cosmos.
• The Conspiracy: It is widely alleged that federal agencies, in collusion with powerful corporate and fossil-fuel interests, systematically suppress, buy out, or classify any inventions that threaten traditional energy grids. Theorists argue that reverse-engineered alien propulsion and limitless power sources have been kept locked away in government vaults for nearly a century.

10. Project MKUltra and the Institutional Cover-Up of Mind Control

• The Claim: Unlike purely speculative myths, the CIA’s MKUltra program was a very real, highly illegal covert human experimentation project that ran from the 1950s through the early 1970s, utilizing unwitting citizens, psychedelics, and psychological torture.
• The Conspiracy: When congressional investigations finally dragged the declassified documents into the light in the 1970s, the sheer scope of the agency’s attempts to unlock mind control and altered states of consciousness verified that the government was willing to explore the fringes of human capability. Extreme extensions of this conspiracy theory claim that MKUltra researchers successfully tapped into supernatural psychic conditioning, possession phenomena, or memory-wiping protocols that remain heavily classified to this day.