Poet, scholar, statesman and soldier, born November 30th, 1554. Educated at Shrewsbury School from the age of ten, and Christ Church, Oxford from 1568 to 1571. He didn't claim a degree, but travelled on the continent instead. He returned and became a courtier.
In 1579, when Queen Elizabeth I had asked him to leave court (he'd objected to her planned marriage to the Duke of Alencon), he went to stay with his sister Mary Herbert, Countess of Pembroke at Wilton. He wrote Arcadia (a long pastoral thing - shepherds and the like) for her. He became a member of Parliament in 1581.
At some time he composed An Apology for Poetry, which wasn't published until 1595, after his death. He also composed Astrophil and Stella (probably started in 1581), a sonnet sequence with 108 sonnets and 11 songs. Shakespeare's sonnet sequence is usually considered the definitive - but Sidney's is much better. It's more experimental for a start (the sonnets are very varied in style, tone and technique), and it's more focussed. It was also, not counting Thomas Watson's Hekatompathia (which was, apparently, rather trite and forced (I've not read it)), the first sonnet sequence in English (inspired, certainly, by Petrarch).
The sonnet sequence also seems to be written, at least in part, to Penelope Devereux (known as 'Stella' it would seem) who was married to Lord Rich. Sidney plays about with the word 'rich' in some of the sonnets, and it's nice to think that he was in love with a woman who couldn't reciprocate his love (very platonic - in fact, completely in keeping with the notions of courtly love). It also seems as if Sidney is quite cutting about Lord Rich, although there is evidence to suggest that he was quite friendly with him in truth, and the whole 'rich' thing is light-hearted banter. I prefer to think that it isn't.
In September 1586, he battled against the Spanish at Zutphen, and received a musket wound, which didn't heal, and of which he died 22 days later.
Quite a cool bloke, all round.