O'Connor, from Ulverstone, Tasmania began his career at the Essendon reserves after being traded by Geelong in the 1991 AFL Draft for ruckman John Barnes.
Even as a young man, O'Connor was known for his massive size (191 cm, 110 kg), considered large even for an AFL player.
Despite his bulk and struggle with weight problems, the big man was surprisingly agile and could take strong contested marks.
He became a centre half forward and strung together a number of impressive games, kicking bags of goals.
The Port Adelaide Magpies picked up O'Connor, where he starred, winning the Magarey Medal in 2001, alongside former St Kilda player Tony Brown.