Killgrew was born at
Lothbury, London, the son of
William Killigrew and his wife Margery (Mary) Saunders, daughter of Thomas Saunders of Uxbridge, Middlesex. In January 1591, he matriculated at
Christ Church, Oxford at the age of 11. He travelled abroad in 1596 and may have become an official of the Privy Chamber in 1601. He was elected MP for
St Mawes in 1601. Killigrew was knighted by
King James I in 1603. In 1604 he was elected MP for
Newport. It is possible that he travelled to
Jamestown in 1604. His name appears in the
Second Charter of Virginia as a backer. In 1606 he was appointed ambassador to the
United Provinces. In June 1612, Killigrew was noted as "one of
Carr's favourites" according to John Chamberlain. The following May, he was committed to the
Fleet Prison for an unknown offence. Having become famous for his concoctions of drugs and cordials, he was at first suspected of complicity in the death of
Sir Thomas Overbury in September 1613, but was subsequently officially exonerated. In 1614, Killigrew was elected MP for
Helston. On 12 May that year, he was involved in an altercation in the House of Commons. In July, he was appointed Keeper of
Pendennis Castle,
Falmouth, Cornwall, and a
JP that same year. He is recorded as fighting a duel with Captain Burton in 1618. In October that year he was appointed an Officer of Protonotary of Chancery, and in December the following year was mentioned favourably by
Buckingham. In 1621, Killigrew was elected again MP for Newport. In 1622 he succeeded his father to become farmer of the profits from seals in King's bench and common pleas which was worth at least £560 a year. He was elected MP for
Penryn and was appointed
Deputy Lieutenant for
Cornwall in 1624. In 1625 he was elected MP for
Cornwall. He was also appointed Ambassador to the
United Provinces in September 1625, but this was not taken up by December that year. In 1626, he was elected MP for
Tregony in 1626. In 1628 he was elected MP for
Bodmin and sat until 1629 when King Charles decided to rule without parliament for eleven years. He was appointed Vice-Chamberlain to Queen
Henrietta Maria in 1630. Killigrew was a knight of
Arwenack in
Falmouth, Cornwall. He died a wealthy man in 1633 in Bath, Somerset, with the probate of his will on 12 May. ==Family==