Source: Web Gallery of Art

Master of the St. Bartholomew Altar
Altarpiece of St. Thomas

1501
Oak, 143 x 106 cm (central panel), 143 x 47 cm (each wing)
Wallraf-Richartz Museum, Cologne
Gift of Peter Rinck to the Carthusian church of St. Barbara in Cologne. 

The figure in the upper part of the left panel appears to be St. Giles.

Also available:

More of St. Thomas