The "Old Firm" Derby is the greatest rivalry in all of football. It extends well beyond the pitch.

Rivalry on a number of levels...religion and politics included...passionate and vile at the same time. Love it.

I know a man who once played for the Under-21 Scottish team. He played part of his short career (ended young because of injury) with the Celtics, and he has told me plenty of stories about this rivalry. Most of the stories I can't mention here, and the tamest of all is simply that when he played with the Celtics, he feared for his live walking through parts of Glasgow, lets just say they weren't 'Celtic' friendly, at night as he might have been recognized by a Ranger fan. It was that point when he really understood the advantages of not playing on the starting XI.

This is probably the top in soccer, but the Glasgow Rangers also shine in Dublin. Many of their "fans" take the ferry to Ireland, seize a couple of pubs or areas during the time of the game, and dare off the law or anyone else who attempts to dislodge them.

Rivalries don't get much deeper than this. Makes Yankees - RedSox look like a schoolyard scrap. Religion and social class stirred into the mix, and the fact the teams play in the same city, put this one at the top.

The rivallry to end all rivalries. This one has a definite body count. The schism between RC and Prod may be ancient and somewhat archaic but it will live forever on the pitch. When I was 16, I worked for my uncle in his pub in Dublin for a summer. After a trip to Belfast we were stopped at the border by the UDR (Ulster Defense Regiment) Basically, a Protestant paramilitary lynch mob backed by the British Army. Legally, they couldn't ask if you were RC or Prod so they'd ask, while pointing a rifle at you, "Who do you support, Rangers or Celtic?"