William de Lamberton, sometimes modernized as William Lamberton, (died May 20, 1328) is Bishop of St. Andrews from 1297 (consecrated 1298) until his death.
Lamberton is renowned for his influential role during the Scottish Wars of Independence.
He campaigns for the national cause under William Wallace and later Robert the Bruce.
Bishop Lambertonis present at the coronation of Robert the Bruce as King Robert I conducted by Bishop Robert Wishart of Glasgow, breaking a law imposed by Edward I that had reduced Scotland to a land opposed to a Kingdom.
Lamberton will go on to have a vital role in the formulation of the Declaration of the Clergy 1310 and the Declaration of Arbroath, which will lead to Scottish Independence.
During his tenure, Lamberton is excommunicated by Rome for his role in the Wars of Independence along with Robert I and the Clergy of Scotland.
However, he is quickly reconciled with the Papacy before his death.