Widely known in the film industry, the man whose nicknames included "Thunder Throat", "The Voice of God" and "The King of Movie Trailers", became known to a wider audience through commercials for GEICO insurance and the Mega Millions lottery game.

LaFontaine said his voice cracked at age 13 in mid-sentence, giving him the bass tones that later brought him much fame and success.

Peterson incorporated many of LaFontaine's ideas for the spots and, in 1963, they went into business together producing advertising exclusively for the movie industry.

LaFontaine claimed that this company first came up with many of the famous movie trailer catchphrases, including his own future signature phrase "In a world ...".

[6] While working on the 1964 western Gunfighters of Casa Grande, LaFontaine had to fill in for an unavailable voice actor to have something to present to MGM.

Some notable trailers which LaFontaine highlighted in the intro on his official website include: Terminator 2: Judgment Day, Shrek, Friday the 13th, Law & Order and Batman Returns.

[9] Lafontaine also did announcing for a few WWE Pay Per View events, as well as the "Don't Try This at Home" bumper and the opening narration for the television shows Team Knight Rider, Renegade and Rambo: The Force of Freedom.

[10]LaFontaine also did other voice work, including as the announcer for the newscasts on WCBS-TV New York, from 2000 to 2001, narrator of The Making of Star Wars documentary from 1977 and the television shows The Third Eye, World's Most Amazing Videos, Boot Camp, America's Most Wanted, Beyond Belief: Fact or Fiction and Fillmore!.

[12] On Friday, August 22, 2008, LaFontaine, a longtime smoker,[13] was admitted to Cedars-Sinai Medical Center in Los Angeles, with a pulmonary embolism and was reported to be in critical condition the following Tuesday.

[16] His final movie trailer voice-over was for Call + Response, a documentary about the global slave trade, for which he donated his talent.

LaFontaine was referenced, with opening clips of his work and several subsequent verbal homages, in the film In a World..., written and directed by Lake Bell.