Others say she's just a figment of people's imaginations.
Debate has raged for more than a hundred years over whether Nessie really lives in the loch.
Mr Pollock won the prize from bookmaker William Hill.
The award's decided every year by The Official Loch Ness Monster Fan Club.
Mr Pollock said: "You could say it was a seal or a deer in the water, but I've seen things like that in the water and it definitely wasn't one of them."