Flavius Josephus, a first century Jewish historian, mentions John - Antiquities, Book 18, ch. 5, par. 2
2. (116) Now, some of the Jews thought that the destruction of Herods army came from God, and that very justly, as a punishment of what he did against John, that was called the Baptist; (117) for Herod slew him, who was a good man, and commanded the Jews to exercise virtue, both as to righteousness towards one another, and piety towards God, and so to come to baptism; for that the washing [with water] would be acceptable to him, if they made use of it, not in order to the putting away [or the remission] of some sins [only], but for the purification of the body; supposing still that the soul was thoroughly purified beforehand by righteousness. (118) Now, when [many] others came in crowds about him, for they were greatly moved [or pleased] by hearing his words, Herod, who feared lest the great influence John had over the people might put it into his power and inclination to raise a rebellion (for they seemed ready to do anything he should advise), thought it best, by putting him to death, to prevent any mischief he might cause, and not bring himself into difficulties, by sparing a man who might make him repent of it when it should be too late. (119) Accordingly he was sent a prisoner, out of Herods suspicious temper, to Macherus, the castle I before mentioned, and was there put to death. Now the Jews had an opinion that the destruction of this army was sent as a punishment upon Herod, and a mark of Gods displeasure against him. Josephus, F., & Whiston, W. (1996, c1987). The works of Josephus : Complete and unabridged. Includes index. (484). Peabody: Hendrickson.
Of course, there was this first century tax collector named, Matthew, who had a thing or two to say about him too
Read Matthew 3:1-17; Matthew 14:3-12 to start. Mark and Luke had something of interest to say as well.