(born 22 August 1905 in Trondheim, died 18 January 1978) was a Norwegian politician from the Conservative Party. He was Prime Minister of Norway from 28 August to 25 September 1963 in a coalition government consisting of the Conservative, Centre, Christian Democratic, and Liberal parties.
He was originally a member of the Liberal Left Party, heading the local party chapter from 1934 to 1935. He was a member of the executive committee of Trondheim city council from 1934 to 1940 and in 1945. In 1945 he had changed to the Conservative Party, heading the party chapter in Trondheim until 1947. Lyng was elected to the Norwegian Parliament from the Market towns of Sør-Trøndelag and Nord-Trøndelag counties in 1945, and was re-elected in 1953. He was then out of parliament for one term, before being elected again in 1958 and 1961, this time from Akershus. From 1955 to 1959 he was a member of Skien city council.
His brief stint as Prime Minister came in August 1963 after the two representatives from the Socialist People's Party joined a slim 76-74 no confidence vote against the Labour cabinet Gerhardsen following the Kings Bay Affair, a series of mining accidents at Ny Ålesund. The socialist vote of no confidence was merely a protest and demonstration, and the Labour cabinet was restored a month later. While Lyng was Prime Minister Ebba Haslund took his seat in parliament.
Although the cabinet Lyng failed to govern for more than a month it did prove that the non-Socialist parties were capable of making a coalition, and following the Norwegian parliamentary election, 1965 the centre-right coalition again assumed power with Per Borten as Prime Minister, and John Lyng as Minister of Foreign Affairs. He was replaced by Svenn Stray in 1970.
Lyng had graduated with the cand.jur. degree in 1927, and later studied in Copenhagen and Heidelberg. Before and after World War II he worked as a lawyer and a judge. He held the post of County Governor of Oslo and Akershus from 1964 to 1970.