Theophilus is Greek for "loved by God." It is the addressee, probably meant figuratively similar to John 3:16 , to whom Luke wrote his two New Testament books: the Gospel of Luke and The Acts of the Apostles. These two books comprise 27% of the entire New Testament.
Many wonder whether Theophilus is the name, or the title, of the person to whom Luke addressed his books. However, Theophilus was most likely a literary expression by Luke to refer to the entire world (as Apostle John independently did), which Luke was very capable of doing as the fabulous writer that he was.