bartholomew, also replaced by nathanael in johns gospel, is THE least mentioned person IN ALL OF THE BIBLE because he only got mentioned 4 times across all 4 gospels, each when the apostles are all listed. the reason he is considored the least mentioned person across all the gospels is because all the other people in the gospels have been mentioned at least twice in each gospel (probably) and nathanael doesnt count because he is just a replacement.
not much is known about bartholomew because he was only mentioned, like i said, when the gospels were listing each of the apostles, but we do know that despite all that, he is still one of the most important people in all of christianity (because he invented it)