Sir William Peryam (1534 – 9 October 1604) of Little Fulford, near Crediton in Devon, was an English judge who rose to the position of Lord Chief Baron of the Exchequer in 1593, and was knighted by Queen Elizabeth I.

Peryam was born in Exeter, the eldest son of John Peryam, twice mayor of Exeter, and his wife Elizabeth, a daughter and co-heir of Robert Hone of Ottery. The year of Peryam's birth is known to history but, as was common in the 16th century, the day and month went unrecorded. Through his mother's sister, Joan Bodley née Hone, Peryam was cousin to Sir Thomas Bodley. Like the Bodleys, the Peryams were early adherents of Protestantism and were also threatened in the time of Marian persecutions. Under Queen Elizabeth however, the family thrived, with William eventually achieving eminence in law and his younger brother John Peryam (1541 – c. 1618), MP, elected to Parliament four times (Barnstaple 1584, Bossiney 1586, Exeter 1589 and 1593) and becoming Mayor of Exeter. The lawyer and politician William Hakewill and the clergyman and author George Hakewill were his nephews.

Young William was first educated in Exeter and then at Exeter College, Oxford where on 25 April 1551 he was elected fellow. He resigned his fellowship some months later and went to London where he eventually studied law at the Middle Temple, being called to the bar in 1565.

A slight setback in his career occurred in 1568 when, after having been summoned to Ireland by Sir Peter Carew to help him prosecute an ultimately successful claim to an Irish barony, Peryam received an unexpected appointment as a judge under the prospective President of Munster, Sir John Pollard. By writing to Sir William Cecil and earnestly petitioning the Privy Council, mentioning his wife and children and delicate state of health, Peryam seems to have been able to avoid the transfer to Ireland altogether. Thereafter, his rise through the legal ranks was steady: in 1575 he became serjeant-at-law for the Michaelmas term, and on 13 February 1581, a Judge of the Court of Common Pleas. His highest office came in January 1593, when he was knighted and promoted to Lord Chief Baron of the Exchequer. Of his knighthood Prince wrote as follows: "Queen Elizabeth of blessed memory, as a signal testimony of her favour and his worth, was pleased to confer upon him the honour of knighthood, but not before he had been twelve years a judge, so cautious was that wise princess in conferring titles, lest they should become cheap and contemptible".

According to the Devon historian Sir William Pole (died 1635), who happened to be one of Sir William Peryam's sons-in-law and through his wife Mary Peryam one of his co-heirs, Sir William Peryam acquired the following estates, all situated near or adjoining one another in or near the parishes of Shobrooke, Crediton and possibly Sandford. All ended up unified in the possession of the Tuckfield family, who made Little Fulford their seat for many generations, either through inheritance from Elizabeth Reynell, wife of Thomas I Tuckfield, a daughter of Richard Reynell and his wife Mary Peryam, daughter and heiress of John Peryam, or by purchase.

Peryam married three times:

Monument to Mary Periham (1567–1605), eldest daughter of Sir William Peryam and 1st wife of Sir William Pole (1561–1635), in the Pole Chapel, Colyton Church, Devon, in which parish is situated Colcombe Castle. The escutcheons show the arms of Pole and Peryam. Text: Heere lieth ye body of Mary late ye wife of Sr. Wm. Pole of Shute knig. beinge ye eldest daughter & one of ye foure heires of Sr. W. Periham of Fulford knig. Lo. Chief Barron of ye Kinge majesties Exchequer. She left behind her 4 son(n)es & 5 daughters unto her saide husband viz John, Periham, Wil., & Franncis, son(n)es, Mary, Katherine, Elizabeth, Ane & Elioner, daughters. She brought unto him also 2 other son(n)es viz Wil., her first child & Arthur being on(e) of ye 3 son(n)es wi.ch she brought at on(e) birth & perished by an unfortunat fall. She dyed ye 2 of May in ye yeere of our Lord 1605 being then of th'age of 38 & on(e) moneth & maried unto her husband 22 yeeres tenn monethes

Mural monument in Heanton Punchardon Church, Devon, to Elizabeth Peryam (1571–1635), daughter of Sir William Peryam and wife of Sir Robert Bassett. Within a lozenge at the top and on an escutcheon to the sinister are shown her paternal arms of Peryam: Gules, a chevron engrailed or between three lion's faces affrontes of the last. The arms of Peryam are also shown on an oval cartouche underneath, impaled by Bassett. The text is as follows:
Memoriae Sacrum
Dominae Elizabethae Bassett uxori Roberti Bassett militis clarissima stirpe oriundi filiae et cohaeredi Gulielmi Peryam militis Schaccarii Regii Baronis primarii Judicic integerrimi et religiosissimi piae prudenti justae patienti modestae castae temperanti constanti hospitali misericordi beneficae pauperum matri et medicae suae familiae conservatrici. Arthurus Bassett armiger filius eius primogenit(us) debitae gratitudinis et observantiae ergo H(oc) M(onumentum) M(atri)? M(aerens) P(osuit) Anno Domini 1635 aetatis suae 64 ad Dominum remeaunt.
Should monuments goe by merit then surely thine,
With pretious stone and orient pearle should shine,
But since thy world of worth ye world doth know,
This marble stone may serve thy name to show.
"Many are the afflictions of the righteous but the Lord delivereth him out of them all". Psal. 34.19.
Ita in fornacem prodiit aurum