Boyd’s Bible Dictionary:
(son of Tolmai). One of the twelve apostles (Matt. 10:3; Mark 3:18; Luke 6:14; Acts 1:13); perhaps Nathanael in John 1:45.
Concise Bible Dictionary:
One of the twelve apostles, who is not referred to by name except in the lists of the twelve (Matt. 10:3; Mark 3:18; Luke 6:14; Acts 1:13). Probably identical with Nathanael: (Compare John 1:45; John 21:2).
Jackson’s Dictionary of Scripture Proper Names:
son of Talmai