According to the Gospel of John, the high priest’s servant whose ear Peter cut off was Malchus.
John 18 names Malchus during Jesus’ arrest. Peter drew a sword and struck the servant, cutting off his right ear. Jesus then told Peter to put the sword away and accepted the arrest. Luke additionally says that Jesus healed the injured ear, although John does not include that detail.
The arrest party is associated with the chief priests and Pharisees, and John identifies Malchus as a servant of the high priest. The Gospel’s naming of a relatively minor participant gives the scene a precise personal detail.
The other Gospels describe the sword attack but do not name the injured servant. John alone identifies him as Malchus and explicitly names Peter as the disciple who used the sword.