John Kaldor (born 1936) is an Australian art collector and philanthropist.
John Kaldor or Calder may also refer to:
John Kaldor, a character in the 1996 novel Awake and Dreaming by Kit Pearson John Calder (1927–2018), Canadian and Scottish publisher John Calder (cricketer) (1951–2010), New Zealand cricketer John Calder (minister) (1733–1815), Scottish dissenting minister and author
See also Jon Caldara, American libertarian activist John Calder Mackay (1920–2014), American post-war real estate developer