Many Old Testament figures are accounted as saints by the Catholic Church.
Today is the commemoration of St. Haggai, one of the twelve prophets of the Old Testament.
Here is his entry in the Roman Martyrology:
1. Commemoratio sancti Aggaei, prophetae, qui, tempore Zorobabel ducis Iudae, populum admonuit, ut domus Domini reaedificaretur, in quam venturus erat thesaurus cunctarum gentium…. The commemoration of St. Haggai, prophet, who, in the time of the leader Zorobabel, admonished the people that the house of the Lord should be rebuilt, in which the treasure of all the peoples would come.