William "Willie" Parkinson Jay (15 January 1855 - 12 December 1940) was an Anglican priest.
Born in Agra, India, he was the son of the Rev. William James Jay. He entered St Catharine's College, Cambridge in 1874, graduating with a BA in 1878 and an MA in 1881.
He was ordained a deacon in 1878 and a priest in 1879. From 1878-1881 he was a curate at St George in the East, and from 1881-1883 at Hackney. From 1883-1889 he was vicar of Christ Church, Watney Street, an East End parish.
In 1889 he was appointed rector of Toppesfield, Essex, and resigned from the school board. In 1894 he moved to Sussex where he was vicar of St Anne's, Eastbourne. He died aged 85 and was buried in Eastbourne.