L0pht Heavy Industries (pronounced "loft") was a hacker collective active between 1992 and 2000 and located in the Boston, Massachusetts area.

There they experimented with their own personal computers, equipment purchased from the Flea [4] at MIT, and items obtained from dumpster diving local places of interest.

[6][7] In time, the members of L0pht quit their day jobs to start a business venture named L0pht Heavy Industries, a hacker think tank.

In 1997, on August 8–10, Mudge, Brian Oblivion, Kingpin, Space Rogue, Stefan, Weld Pond, and John Tan of L0pht discussed recent projects and accomplishments, Windows NT, new projects, emerging trends and shortcomings in technologies, with Q&A session at Beyond HOPE at the Puck Building in New York City.

[9] In the article Jeffrey Hunker, NSC's then Director of Information Protection, said about L0pht, "Their objective is basically to help improve the state of the art in security and to be a gadfly, so to speak."

In January 2000, L0pht Heavy Industries merged with the startup @stake, completing the L0pht's slow transition from an underground organization into a "whitehat" computer security company.

[12] On May 19, 1998, all seven members of L0pht (Brian Oblivion, Kingpin, Mudge, Space Rogue, Stefan Von Neumann, John Tan, Weld Pond) famously testified[13][14][15] before the Congress of the United States that they could shut down the entire Internet in 30 minutes.

[21][22][23][24][25][26][27] At the Defcon 26 hacking conference, held on August 10, 2018 in Las Vegas, seven of the L0pht members sat on a panel entitled "The L0pht Testimony, 20 Years Later (and Other Things You Were Afraid to Ask)".

In fact, L0pht originally shared a space with a hat-making business run by the spouses of Brian Oblivion and Count Zero, and the rental cost was divided amongst them both.