Julian Roger Hallam is a British environmental activist, a co-founder of Extinction Rebellion, cooperative federation organisation Radical Routes, the political party Burning Pink,, Just Stop Oil, and Insulate Britain.

Extinction Rebellion is a UK-founded global environmental movement, with the stated aim of using nonviolent civil disobedience to compel government action to avoid tipping points in the climate system, biodiversity loss, and the risk of social and ecological collapse. Extinction Rebellion was established in Stroud in May 2018 by Gail Bradbrook, Simon Bramwell, Roger Hallam, Stuart Basden, along with six other co-founders from the campaign group Rising Up!