Viliami Tungī Mailefihi (1 November 1887 — 20 July 1941) was a Tongan chief and consort of Queen Sālote Tupou III.
He was the son of Siaosi Tukuʻaho (also see: Lakalaka), who served as Prime Minister of Tonga from to 1890 to 1893. Tungī's grandfather was Tungī Halatuituia. The line of Tungī chiefs from Tatakamotonga was descended from the then defunct Tuʻi Haʻatakalaua which in that time was more or less seen as an associate of the Tuʻi Tonga. As such they had the following from the people of Muʻa if not from the whole Hahake district. Concerning his mother's side, Mele Siuʻilikutapu, she was the granddaughter of the Tuʻi Vavaʻu: Fīnau ʻUlukālala (III, Tuapasi).
He was selected by King Siaosi Tupou II to marry his oldest daughter and heir, Sālote, even though she was 12.5 years younger than he. The wedding took place on 19 September (Christian ceremony) and 21 September (Tongan ceremony, the tuʻuvala) 1917, less than a year before Siaosi would die and Sālote would be crowned as queen.
The marriage was a success. Tungī's personality and status did a lot to elevate the esteem of the people towards their queen. Furthermore, their children born would carry the combined bloods of the 3 major Tongan royal dynasties. Tungi would always be remembered as very generous to all his relatives. His death in 1941 was a heavy blow not only to Queen Salote but to all Tungi's relatives and kainga.
Despite the respect he had for his wife, Tungī had many girlfriends everywhere around. But Tulu from his hometown Muʻa was his favourite and he visited her perhaps every week. Also that day when he and Sālote had welcomed a contingent of Australian mariners from the airport. While Sālote returned town with them, he used the opportunity to have a short detour to Muʻa. On this specific occasion he collapsed while with her.
Tungī was educated at Tupou College, Tonga and Newington College, Sydney. He was a follower of the Methodist Church. Tungī was a CBE and was also prime minister of Tonga from 1923 until his death.