Portrait of a Carthusian is a painting in oils on oak panel by the Early Netherlandish painter Petrus Christus in 1446.

Because the monk's body is turned to his left, he must look over his right shoulder to gaze at the viewer, creating a somewhat cumbersome diagonal pose.

Many art historians believe the fly to hold religious symbolism, functions as connotations of sin, corruption, mortality, etc.

However, halos are extremely rare in Early Netherlandish painting and the one in Portrait of a Carthusian had long been an object of speculation.

Finally in 1994, in preparation for the Met's exhibition Petrus Christus: Renaissance Master of Bruges, the authenticity of the halo was publicly examined by a panel of Early Netherlandish specialists and determined to be an addition.

[3] The team generally agreed that halo was probably added in Spain in the 17th century—imitating an Italian trend—where it became part of the collection of Don Ramon de Oms, viceroy of Majorca, who sold the work to American industrialist Jules Bache in 1911.