Phase 3, Phase III or Phase Three may refer to:

Media[edit]

• Marvel Cinematic Universe: Phase Three, eleven American superhero films from 2016–2019
• Phase 3: Thrones and Dominions, a 1995 album by Earth
• Phase III (album), a 1972 album by the Osmonds
• Phase Three (album), a 2003 album by the Riverdales

Other[edit]

• MediaWiki's unofficial name during 2002 until 2003
• Phase III clinical trials, the third of the phases of clinical research
• Phase 3 Eclipse, an American ultralight aircraft
• Phase 3 Productions
• Phase 3 metro station
• Phase III Offensive