Venerius, patron saint of lighthouse keepers, is memorialized on May 4. Nobody seems to know why he was chosen as the patron of lighthouse keepers. Perhaps he was particularly devoted to maintaining the Church as a beacon of light and hope in the world. This theory is supported by the fact that he is best remembered for his staunch support of John Chrysostom's fight against greed and corruption amongst the clergy.

Perhaps even when they made him a saint, which was a very very long time ago, nobody remembered much about poor Venerius. At any rate, not much is known about his life. He was ordained as a deacon by Saint Ambrose, and later (around A.D. 400) became the second bishop of Milan.

Venerius died of natural causes in 409. In 1579, his relics were translated to the Cathedral of Milan by Charles Borromeo. The other notable fact about Venerius is that he is listed as one of the oil-bearing saints or Elaephori, which means that at some point miraculous properties were ascribed to his remains.


Sources:
users.erols.com/saintpat/ss/0504.htm
www.catholic-forum.com
www.catholic.org