Lucas Marsh is a 1.5 hectare Local Nature Reserve in Oadby in Leicestershire.

[1][2] It is part of Brock's Hill Country Park, and is owned by Oadby and Wigston Borough Council and managed by the Leicestershire and Rutland Wildlife Trust.

[3] The marsh is dominated by greater willowherb and common reed, while there are also areas of rough grassland, a hedge, trees and scrub.

Butterflies include small tortoiseshell, speckled wood, peacock and orange tip.

[3] There is access by a footpath from Washbrook Lane.