Jehoash Ssibakyalyawo Mayanja Nkangi or Joash Mayanja Nkangi (22 August 1932 – 6 March 2017) was a Ugandan lawyer, civil servant and politician.
At the time of his death, he was the immediate past chairman of the Uganda Land Commission.
He previously served as a cabinet minister in several ministries in the Cabinet of Uganda.From 1962 until 1993, Mayanja Nkanki served as the "Katikkiro" (prime minister) under Sir Edward Muteesa II, the Kabaka of Buganda, who reigned from 1939 until 1969.
In 1993, when the Kingdom of Buganda was re-instated, he was instrumental in the installation of the present monarch, Ronald Muwenda Mutebi II.