Lucas Achtschellinck, was a Flemish landscape painter. He is counted among the landscape painters active in Brussels referred to as the School of Painters of the Sonian Forest who all shared an interest in depicting scenes set in the Sonian Forest, which is located near Brussels.

He was born in Brussels and was possibly the grandson of the landscape painter Lukas Achtschelling. He was registered in the Brussels Guild of Saint Luke on 26 October 1639 as a pupil of a Pieter van der Borcht. The 17th century Flemish biographer Cornelis de Bie mentioned that Lucas Achtschellinck also studied with the Brussels landscapist Lodewijk de Vadder but this is not confirmed by Guild records. However, stylistically the two artists are quite close.

Achtschellinck likely travelled abroad after completing his apprenticeship since he only became a master in the Brussels guild in 1657. On 13 March 1674 he married Anna Parys. He remained active in Brussels and in 1687 he was the deacon of the Brussels guild. He was successfully and employed 8 pupils including Théobald Michau between 1659 and 1686.

He died in Brussels.