|Born||2 April 1564|
|Died||17 June 1614 (aged 50)|
|Occupation(s)||Jesuit priest, musicologist, writer|
Born in Dublin, Bathe lived at Drumcondra Castle, County Dublin, a member of a leading Anglo-Irish family. He was the eldest surviving son of John Bathe, Chancellor of the Exchequer of Ireland, and his first wife Eleanor Preston, daughter of Jenico Preston, 3rd Viscount Gormanston and Lady Catherine Fitzgerald; his paternal grandfather was James Bathe, Chief Baron of the Irish Exchequer, whose second wife, William's grandmother, was Eleanor Burnell of Balgriffin  His brother John Bathe was an Irish representative at the Royal Court in Madrid in the early 1600s. When William's father died in 1586 the family were among the biggest landowners in Dublin, although their wealth and influence notably declined in the next generation. : 16 William inherited the family estates on his father's death, but on entering the priesthood he transferred them to John, the next brother in age, in 1601. 
Bathe was trained as a musician and linguist at Oxford, where he wrote A Briefe Introductione to the True Art of Musicke (1584), which was revised as A Briefe Introduction to the Skill of Song (c.1596) – the first printed treatise on music in the English language.  Following a long-standing family tradition, he also studied law at the Inns of Court in London. For a time he enjoyed the favour of Queen Elizabeth I, to whom he presented a harp of his own design.  The Queen made him a number of grants of land, thus adding further to the extensive Bathe holdings: but royal favour ceased after 1598, on the discovery that William had entered the priesthood. The decision of a third Bathe brother, Luke, to become a priest did nothing to restore the family to favour (under the name Fr Edward Bathe, Luke became a prominent member of the Capuchin order). Apart from the religious issue, the close friendship between Hugh O'Neill, Earl of Tyrone and Sir William Warren, who married William's widowed stepmother Jenet Finglas, raised serious questions about the family's loyalty to the English Crown during O'Neill's rebellion, popularly known as the Nine Years War.  William is not known to have visited Ireland after 1601.
He taught languages in Europe and wrote one of the world's first language teaching texts, Janua Linguarum (The Door of Tongues, 1611), a juxtaposition of words and pictorial representations of them. It proved so popular that it was translated into nine languages within twenty years. The Czech educator Comenius based his work Janua linguarum reserata on this text.