The apostle who reaches for a knife in The Last Supper is Peter.
Leonardo places Peter behind the seated John, leaning forward with an agitated expression. His right hand appears to reach for a knife held near Judas, while his other hand touches John’s shoulder. The gesture is commonly interpreted as a visual reference to Peter’s later violent reaction during Jesus’s arrest in Gethsemane, when Peter cuts off the ear of the high priest’s servant.
The knife is easy to miss because Peter is partly hidden behind John and because the mural has suffered severe deterioration and repeated restoration. Early copies of the composition, especially those made when more detail was visible, help scholars understand features that are now difficult to read on the original wall.
A common mix-up is Judas, who sits close to the knife and is traditionally identified by his backward movement and the spilled salt. John is the youthful figure leaning toward Peter, while James the Greater, Philip, and Thomas form the group immediately to Jesus’s other side.