Captain William Henry O'Shea (1840 – 22 April 1905) was an Irish soldier and Member of Parliament.

He is best known for being the ex-husband of Katharine O'Shea, the long-time mistress of the Irish nationalist leader Charles Stewart Parnell.

Around 1880, his wife, Essex born Katharine O'Shea, entered into a relationship with the Irish nationalist leader Charles Stewart Parnell, with whom she had three children.

In 1882 when the Liberal government was secretly negotiating with Parnell for the terms of his release from Kilmainham Gaol where he was being held on suspicion of "treasonable practices", the President of the Board of Trade, Joseph Chamberlain, chose O'Shea as its intermediary, unaware of Parnell's affair with Mrs O'Shea or of the fact that the newly born first child of their liaison was dying.

[3] However, he only filed for divorce on 24 December 1889 after his wife's aunt, from whom he was expecting a large inheritance, died earlier that year leaving her estate in trust for his wife (thus allegedly violating the terms of O'Shea's marriage contract).