I think I may have it.
Frank "The Running Fullback" McMillan.
Here's where I found it -
http://www.angelfire.com/mt/hort/innovators.html
7. Frank McMillan
"The Running Fullback"
Position: Fullback
Played for: Western Suburbs, NSW, Australia <table border=2> <tbody> <tr> <td>
</td> <td>This Magpie legend changed the role of fullbacks and backline play, when he elected to play in the front line in attack. The move would give his side an extra man in the line, and create an overlap. This was lethal when combined with brilliant legend Vic Hey at five eighth. Hey was a visionary, who could read the play like no other. His deft passes were perfect food for McMillan, who would pass a defensive line with a full threequarter line available to use to continue progress. The combination, and McMillan's extra man play netted Wests 3 premierships, and both men the honour of captaining their country. Some of Australia's greatest legends, like Clive Churchill, Les Johns, Ken Thornett, Greame Langlands, Graham Eadie and Garry Belcher all perfected this style to great career advantage.
It is the basis of attacking fullback play today. </td></tr></tbody></table>