One of the Old Testament leaders recognized by the Roman Catholic Church as a saint is Joshua.
The 2004 Roman Martyrology lists his name on September 1 with the following description:
Commemoration of Saint Joshua, son of Nun servant of the Lord, who, with the imposition of hands by Moses, was filled with the spirit of wisdom, and, after the death of Moses, admirably led the people of Israel along the course of Jordan to the promised land.
The Catechism of the Catholic Church affirms this tradition of honoring the lives of Old Testament saints:
The patriarchs, prophets and certain other Old Testament figures have been and always will be honored as saints in all the Church’s liturgical traditions.
CCC 61
Who was Joshua?
The Catholic Encyclopedia offers the following summary of his life:
(First called Osee; Septuagint ‘Iesoûs, first Aúsé), the son of Nun; the genealogy of the family is given in 1 Chronicles 7:20-27; it belonged to the tribe of Ephraim. Joshua commanded the army of Israel, after the Exodus, in its battle with Amalec (Exodus 17:9-13), was called the minister of Moses (xxiv, 13), accompanied the great lawgiver to and from Mount Sinai (xxxi, 17) and into the tabernacle of the covenant (xxxiii, 11), and acted as one of twelve spies whom Moses sent to view the land of Chanaan (Numbers 13:9). On this occasion Moses changed his servant’s name from Osee to Joshua (Numbers 13:17). The new name most likely means “Jahweh is salvation“. Joshua and Caleb alone spoke well of the land, even though the people wished to stone them for not murmuring and these two lived on (Numbers 14:38).
One of his most important roles was that of successor of Moses:
Joshua was chosen by God to succeed Moses. The words of the choice show the character of the chosen (Numbers 27:17-18). Before Eleazar and all the assembly of the people Moses laid hands on Joshua. Later this soldier was proposed by Moses to the people to lead them into the land beyond the Jordan (Deuteronomy 31:3), and was ordered by the Lord to do so (xxxi, 23). After the death of Moses, Joshua was filled with the spirit of wisdom and was obeyed by the children of Israel (Deuteronomy 34:9). The rest of story of Joshua is told in the Book of Joshua.
Joshua is a great figure from the Old Testament and the Church remembers him on September 1.