There aren't all that many famous Dempsters around, nor have there been all that many in the past. In the UK two make it to the multi-volume Dictionary of National Biography, and only one of those is in the current Chamber's Biographical Dictionary. He is best described as Infamous.
Obviously the family included the usual crop of sheep stealers and the like (though to be one-up the Dempster's played Robin Hood and actually went in for kidnapping monks), but not really anyone roguish enough to be celebrated in song or story.
However, there are a few Dempsters worth remembering, and here are the stories of some of them. If you know of more, please send me their story.
Professor Thomas Dempster (c1575-1625)
George Dempster of Dunnichen (1732-1818)
Inspector W.J.D. Dempster RCMP (1876-1964)
Charles Stewart (Stewie) Dempster (1903-1974)
© James Dempster 1997