Pentillie Castle is a grade II* listed[1] country house and estate on the bank of the River Tamar in Paynters Cross, near to St Mellion, in Cornwall, England, in the United Kingdom.

Repton envisaged an impressive Gothic Revival castle, and as a consequence of his vision, Pentillie was extensively enlarged in 1810, with the construction of three new wings to the west side of the old structure.

In 2009 and 2011, Pentillie was the subject of a Channel 4 television programme presented by hotelier Ruth Watson as part of her Country House Rescue series.

In 2013, archaeologists discovered human remains at the Grade II* listed mausoleum at Pentillie, despite suggestions in the 19th century that all bodies had been removed from the site.

Air Chief Marshal Sir William Alec Coryton KCB, KBE, MVO, DFC, RAF was born at Pentillie.