No doubt some people will be tempted to nominate the usual gang of notorious criminals who, horrible though their crimes may be, caused no measurable damage to the functioning of the Canadian polity.
No doubt others will name whichever prominent politician whose ideology disagrees with them, no matter their actual effect on the peace, order and good government of the Dominion.
But everybody has an idea about who the worst Canadian of all time is.
Whoever that person might be, he is likely someone whom most Canadians have never heard of, but whose influence on public policy has been especially malign.
Maurice Strong would be such a candidate, because his visions of an authoritarian world government, and his backroom influence, have had significant influence on the drafters of the Kyoto Accord, the International Criminal Court, and other such unaccountable transnational institutions and agreements.
Who else can you think of?