The St John Altarpiece (German - Johannesaltar, Johannestafel or Johannesretabel) is a c. 1455 oil-on-oak wood panel altarpiece by the Early Netherlandish painter Rogier van der Weyden, now in the Gemäldegalerie, Berlin. The triptych is linked to the artist's earlier Miraflores Altarpiece in its symbolic motifs, format and intention.
The panels show – from left to right – the birth of Saint John, the baptism of Christ by John in Jordan, and the beheading of John, with Salome receiving the disembodied head on a plate. Each panel is set within painted archivolts, which contain painted reliefs depicting statuettes of the apostles, and scenes from the lives of both Christ and John, with the overall theme of salvation. The faux sculptural reliefs are painted in grisaille, and give the impression that the scenes are set within a church.
There are two extant versions of the altarpiece, almost equal in size, leading to complexities in establishing attribution and authenticity. The version in Berlin is considered the original, that in Frankfurt a near contemporary copy.