John Rashleigh II (1554 – 12 May 1624) of Menabilly, near Fowey in Cornwall, was an English merchant and was MP for Fowey in 1588 and 1597, and was High Sheriff of Cornwall in 1608. He was the builder of the first mansion house on the family estate at Menabilly, near Fowey, Cornwall, thenceforth the seat of the family until the present day. Many generations later the Rashleigh family of Menabilly in the Return of Owners of Land, 1873 was listed as the largest landowner in Cornwall with an estate of 30,156 acres (122.04 km2) or 3.97% of the total area of Cornwall.
He was the only son of John I Rashleigh (d.10 August 1582), a merchant at Fowey in Cornwall (the 2nd son of Philip I Rashleigh (died 1551) of Fowey) by his wife Alice Lanyon (d.20 August 1591) (whose 1602 monumental brass survives in Fowey Church,) daughter of William Lanyon by his wife Thomasine Tregian, daughter of Thomas Tregian.
Philip I Rashleigh (died 1551) of Fowey, by his wife Genet Leigh, daughter of Thomas Leigh of South Molton, Devon, was the 2nd son of John Rashleigh (died 1528) of Barnstaple in Devon, whose great-grandfather had been John Rashleigh alias Bray, the younger son of Robert Rashleigh (died pre 1390) of Rashleigh, Wembworthy, Devon, by his wife Matilda.
The de Rashleigh family had originated in the 14th century or before at the estate of Rashleigh in the parish of Wembworthy in Devon, of which the Barnstaple family was a later branch and of the latter the Fowey branch was a junior, but much the most successful, branch. Philip I Rashleigh (died 1551) had been the first to settle at Fowey, having purchased from the crown in 1545 at the Dissolution of the Monasteries the manor of Trenant, near Fowey, formerly a possession of nearby Tywardreath Priory. His eldest son Robert inherited the lordship of Trenant and made his seat at Coombe within that manor and continued the senior, but less successful Cornwall line of Rashleigh of Coombe until 1698 when his descendant Robert Rashleigh (1645–1708) (whose monumental inscription survives in Fowey Church) the last in the male line, sold Coombe to his cousin Jonathan Rashleigh of Menabilly, who sold it out of the family in 1699.