A lot of misinformation and disinformation that is shared in western democracies originates from Russian sources in the IRA, the Internet Research Agency, and other bot farms in different parts of Europe that exist to sow false claims and try to spread them. In the American context, a key spreader of misinformation that also gets a lot of attention is former President Donald Trump, with an account that spreads a lot of misinformation.
I would say the primary organization that is really attempting to influence elections in Canada and the United States is the Russian IRA.