The Earth Liberation Front, or ELF, is a group of activists that are classified as eco-terrorists by the Federal Bureau of Investigation. Though there is no leader, central organization or governing body, groups around the world follow a set of guiding principles to carry out acts of eco-sabotage in the name of protecting the environment.

Urban sprawl is a top target of ELF, as evidenced by the Seattle home fires of March, 2008. The incident involved the burning of multi-million dollar houses in Seattle, Washington, for which ELF claimed responsibility.