The Cross of Tau, named after the Greek letter it resembles, is a form of the Christian cross symbol.
The shape of the letter tau or T was interpreted as representing a crucifix from antiquity. The tau was also considered a symbol of salvation due to the identification of the tau with the sign which in Ezechiel 9:4 was marked on the forehead of the saved ones, or due to the tau-shaped outstretched hands of Moses in Exodus 17:11.
St. Anthony of Egypt bore a cross in the form of a tau on his cloak. The Tau Cross is most commonly used in reference to the Franciscan Order and Saint Francis of Assisi, who adopted it as his personal coat of arms after hearing Pope Innocent III talk about the Tau symbol. It is now used as a symbol of the Franciscan Order.