Scroll down for an index of records. Click on green links of those that are active
Canada Census Index: 1921 census for Canada is online for free at Ancestry.ca. Choose province, then district one by one within that region. Slow and tedious, but at least it gives some help.
New 1921 at Library & Archives of Canada
1861 for Canada West (Ontario), Canada East (Quebec), Prince Edward Island, Nova Scotia, New Brunswick.
1841 census for Canada West (Ontario)
There are even earlier census in some locations, but not linked to one web site. Usually found by individual counties. The earliest census 1799 for Canada had only one Gillespie on it re William Gillespie in Frontenac County. Gillespies were in Newfoundland in 1600s.
WESTERN CANADA – click on name of province to find records
Prince Edward Island