Robert Muller, Mueller or Müller may refer to:

• Robert Muller (United Nations) (1923–2010), Belgian-French United Nations civil servant
• Robert Muller (screenwriter) (1925–1998), German-born British screenwriter
• Robert Mueller (born 1944), American Director of the FBI and special counsel
• Bobby Muller (born 1946), American peace activist
• Robert Müller (ice hockey) (1980–2009), German ice hockey goaltender
• Robert Müller (footballer) (born 1986), German footballer
• Robert Enrique Muller (1881–1921), official photographer for the United States Navy

• Moeller, a surname
• Moller (including also Möller and Møller), a surname
• Mueller (surname)
• Müller (surname)

• Robert Mueller Municipal Airport, a former airport in Austin, Texas, US
• Robert Meller (1564–1624), English politician