The apostle who points his index finger upward in The Last Supper is Thomas.
Thomas appears immediately to Jesus’s left, in the group with James the Greater and Philip. His raised index finger is one of the mural’s most recognizable gestures and is commonly read as a foreshadowing of his later doubt about Jesus’s Resurrection. In the Gospel of John, Thomas asks to see physical evidence before believing that Jesus has risen.
Leonardo uses the apostles’ varied poses and gestures to turn Jesus’s announcement of betrayal into a scene of individual reactions. Thomas’s upward-pointing finger contrasts with James’s startled, raised arms and Philip’s pleading posture. These details help viewers distinguish figures who might otherwise blend into the crowded composition.
The gesture should not be confused with a general blessing or with Jesus’s own central role. Thomas is one of the apostles in the trio directly beside Christ, and his finger is part of Leonardo’s visual characterization. The painting’s deterioration and later restorations make some details harder to see than they were originally.