William Jarvis Willis (1839 – 1 March 1884) was a 19th-century Member of Parliament in the Rangitikei region of New Zealand.
During the confrontations with Maori, he was major in command of militia and volunteers in Rangitikei and Manawatu.
In 1879 Willis resigned from the bench to contest Rangitikei seat as supporter of John Hall.
He defeated Charles Lendrick MacLean but because of poor health he resigned early in 1880.
Willis died at his family home of Woodendean, at Greatford near Bulls in 1884, aged 44.