Champions of any single seat formula (not karts), who hit the wall on the exit of the final chicane in Montreal, in any single seater race car, between the beginning of 1999 until today.
Alonso did thump the wall and retire this year, but it wasn't the Champion's Wall. Montoya has spun there but didn't hit the wall. Villeneuve hit it in 1999, and was F1 champion in 1997. Ralf hit it in 1999 during practice, and was champion in Japanese F3000 in 1996, and German F3 the two years preceding.
Button hit the wall this year and was British Formula Ford champion in 1998, I think. Michael Schumacher hit it in 1999 and has won umpteen billlion championships.
So, thus far we have 4: Button, both Schumachers and Villeneuve. Not there yet though.