Do I need to file a US tax return just because my employer is based in the US, even if I never go there?

Generally, no, simply having a US-based employer doesn't, by itself, create a US tax filing obligation for someone who is a Canadian resident, not a US citizen or green card holder, and performs all their work physically in Canada. US tax filing obligations are generally tied to US citizenship, US residency, or US-source income, and wages for services genuinely performed outside the US typically aren't treated as US-source income requiring a US return.

Where this can change is if any US tax was actually withheld from your pay by mistake, since you might need to file a US return to claim a refund of tax that shouldn't have been withheld in the first place, or if you have some separate connection to the US beyond the employment relationship, such as US-source investment income or past US residency. The mere existence of a US employer paying you from a US bank account isn't, on its own, enough to trigger a filing requirement.

Because US filing rules and cross-border employment situations can get genuinely complicated, and the consequences of getting it wrong on either side of the border can be significant, confirming your specific situation with an advisor familiar with both countries' rules is worthwhile rather than assuming based on general rules alone.