Peter Thomas Mahon QC (1 November 1923 – 11 August 1986) was a New Zealand High Court judge.

His assessment of the airline's witnesses having engaged in "an orchestrated litany of lies" is one of the most well-known quotes in New Zealand, brought him offline with the establishment and made him a national hero.

In 1983 the Judicial Committee of the Privy Council held that Mahon had made serious mistakes of law through acting in excess of his jurisdiction and in breach of natural justice by going on to make findings of a conspiracy by Air New Zealand to cover up the errors of the ground staff.

This conclusion was reached on the point of law that those accused of the conspiracy had not been given an opportunity to contest it in Mr Justice Mahon's inquiry: his conclusions that documents had been suppressed, and that witnesses had lied, were not set aside as an appellate court is not permitted to investigate findings of fact.

In 2008, Mahon was posthumously awarded the Jim Collins Memorial Award by the New Zealand Airline Pilots Association for exceptional contributions to air safety, "in forever changing the general approach used in transport accidents investigations world wide.