Edward Teller (1908–2003) was a Hungarian-born American theoretical physicist, often called the "father of the hydrogen bomb," who helped found Lawrence Livermore National Laboratory and became one of the most influential and divisive scientific advisers of the Cold War. He appears in the UAP record as a participant in a secret 1949 Los Alamos conference on the green fireballs and as a figure in claims by others, above all Bob Lazar's account of how he came to work at the alleged S-4 site.

Born in Budapest on January 15, 1908, Teller studied chemical engineering at Karlsruhe and earned a doctorate in physics under Werner Heisenberg at Leipzig in 1930. He moved to the United States in 1935 to teach at George Washington University and joined the Manhattan Project at Los Alamos in 1943, where he pressed for a fusion weapon. With Stanislaw Ulam he devised the Teller–Ulam design in 1951, first tested in the Ivy Mike explosion of 1952. He helped found the Livermore laboratory that year and directed it from 1958 to 1960. His 1954 testimony against J. Robert Oppenheimer's security clearance estranged him from many colleagues. In later decades he championed nuclear power and missile defense, including President Ronald Reagan's Strategic Defense Initiative and an X-ray laser pursued by his group at Livermore. He received the Presidential Medal of Freedom in 2003 and passed away at Stanford that September.

On February 16, 1949, Teller joined Los Alamos director Norris Bradbury, meteor specialist Lincoln LaPaz, military officers and an FBI representative at a classified conference on the green fireballs then being reported over New Mexico's atomic installations. The transcript, released by the Department of War in July 2026, shows him pressing LaPaz on speed, brightness and the absence of sound, remarking that the reports sounded like "everything else but meteors," and spending about twenty minutes at the blackboard. He suggested that if the fireballs were not a material body, an "electron phenomenon" might explain them. He also said flying discs were reasonably explained as weather balloons, and the meeting ended without an identification.

Lazar has said he first met Teller in 1982 outside a lecture at Los Alamos, where Teller was reading a local newspaper story about Lazar's jet-powered car, and that in 1988 Teller answered his job inquiry by naming a contact who led to an interview with the contractor EG&G and, by Lazar's account, to work on recovered craft near Area 51. Teller never publicly confirmed the story. A brief clip of Teller being asked about Lazar and declining to discuss him has circulated in Lazar documentaries for decades; a longer cut of the exchange prompted fresh debate in 2026. Separately, British barrister Jonathan Caplan writes in his 2026 book that Teller and three other Hungarian émigrés who jokingly called themselves "the Martians" later worked on Majestic projects, a claim no released official record supports.

Teller's documented part in UAP history is that of a leading weapons physicist who took the green fireballs seriously enough to work through their physics and still could not account for them. His stature at Los Alamos and Livermore is also why later stories, from Lazar's hiring account to claims about secret programs, invoke his name, though they come from others rather than from Teller himself.