William Mathers Jack, OBE (1 May 1890 – 14 September 1982), known as "Silent Billy", was an Australian politician.

After arrival in Australia, Jack became a grocer and businessman in North Sydney, and was elected to Willoughby Council.

In 1949, he was elected to the Australian House of Representatives as the Liberal member for North Sydney, a position he held until his retirement in 1966.

[2] However, he was a very popular local member, noted for his strong constituent service, and retired without having lost an election.

In the New Year Honours of 1968, he was appointed an Officer of the Order of the British Empire for services to the Parliament and the community.