Who is the author of the poem The tragicall historye Of Romeus And juliet?

William Shakespeare.

However, the tale of Romeo and Juliet had earlier origins. For example, the storyline is very similar to The Tragical History of Romeus and Juliet, a tale written in verse by Arthur Brooke in 1562, which was subsequently re-written in prose by William Painter in 1582, and re-named Palace of Pleasure.

Yet even Brooke's The Tragical History of Romeus and Juliet was itself basically a translation of Pierre Boaistuau's version found in his Tragic Histories. (1559) But Boaistuau did not pen the story first! This sad tale of romantic love between two young people from two different feuding families can be traced to the story of Mariotto and Giannozza (1476) by Masuccio Salernitano! But! The Romeo & Juliet story has even earlier roots! Going back centuries! For more information, see 'Related links' below.