Ok, a blatant rip-off of the “Greatest Briton” thread, but I couldn’t resist. Here’s my top 10 (in no particular order):
I know there are quite a few Canadian Dopers. Who’s on your list?
What the heck, I’ll play!
Neil Young, Neil Peart, Geddy Lee, Bob & Doug and six other tuc-wearin’ hosers!
Take off, eh!
I don’t get it. Are we including ALL TIME Canadians? If so, man, David Suzuki? John Ralston Saul?? Holy moly… there ARE Canadians who did stuff other than host TV shows and write so-so books, ya know. 
Assuming we include Canadians throughout history:
1. Sir John A. Macdonald
Absolutely #1 on the list beyond any doubt or question; to be quite honest, this is really “Sir John A. and a list of nine distant runners-up.” Literally was the man who led in the creation of the country as it exists today; far more the father of his nation than George Washington was.
2. Pierre Trudeau
The unquestioned leader of the movement that made Canada the sort of nation it is now; bilingual, socially liberal, multicultural. Successfully fought off the separatist movement.
3. Sir Sanford Fleming
What time is it? If you know, thank this guy.
4. George-Etienne Cartier
Along with MacDonald, the father of our country. The reason Canada is bilingual and not just a big New Zealand.
5. W.M. Aitken, Lord Beaverbrook
Canada’s greatest captain of industry and one of the most important Allied leaders of World War II. Depending on how you weigh contribution to the world vs. to Canada, could rank #1.
**6. (Tie) Banting and Best **
Responsible for saving millions of lives.
8. Mordecai Richler
Canada’s greatest literary figure by a margin of about a hundred percent.
9. Wayne Gretzky
Canada’s greatest athlete, the greatest Canadian celebrity of modern times, and a cornerstore of modern Canadian legend.
10. Yousuf Karsh
The greatest portrait photographer who has ever lived.
Honorable mentions: Emily Carr, Robertson Davies, J.J. Hill, Tom Thompson, Denys Arcand, Norman Jewison, Margaret Laurence, Margaret Atwood, Stephen Leacock, Farley Mowat, Marshall McLuhan, John Polanyi, Sir William Osler, Terry Fox, Lester Pearson, Norman Bethune, Douglas Shearer, Neil Young, Leonard Cohen, Ferguson Jenkins, Maurice Richard, Gordie Howe, James Naismith, Roch Carrier, Sir William Lyon Mackenzie King, Sir Wilfrid Laurier.
Jesse Palmer. You can put Joe Sakic and Patrick Roy up around there too. But Jesse’s the man.
Oh, that’s easy:
John Byner, of course.
Here’s a list of famous (greatest?) Canadians.
John A. would be my first choice, but I’d make sure Lieutenant-General Sir Arthur Currie gets into the top ten.
Joe Shuster, co-creator of Superman, gets at least an honorable mention.
I suppose we’d have to include Edith Prickley, Perini Scleroso, Mrs. Falbo, and Johnny LaRue as well.
I think you have all covered the list for me pretty well. Nobody has mentioned Kim Campbell. She became the first female Prime Minister, but she wasn’t elected and she couldn’t hang on to it. It’s too bad that our first female pm was so startlingly bad at it.
Welcome, Muck Muck! Wave to the Rockies for me!
Bobby Orr.
Alex Trebek? Lorne Greene?
Gordon Lightfoot
GingerOfTheNorth, no contest.
LORNE MICHAELS IS THE GREATEST CANADIAN WHO EVER LIVED!!!mmmkay. Glad I got that off my chest.
From an American’s perspective, I’d have to say Gordon Sinclair.
Dudley Do-Right
The Kids in the Hall
Me! (ain’t duel citizenship grand?)
Or dual. Whatever.
James Dohan? Bill Shatner? The Great Bird? My bet? Steve Smith
Just the opinion of an uninformed American