The de Grey Mausoleum in Flitton, Bedfordshire, England, is one of the largest sepulchral chapels in the country.

The mausoleum contains over twenty monuments to the de Grey family who lived in nearby Wrest Park.

The cruciform mausoleum has its nave set against the north side of the chancel of the adjacent church of St John the Baptist and its south transept overlaps the east end.

[1] The architect Edward Shepherd worked on the building during 1739–40.

It is a Grade I listed building,[2] a scheduled monument,[3] and is in the guardianship of English Heritage who open it to the public.