This is, indeed, a Heteroptera bug.
Luckily, this is not a kissing bug (which could be infected with _Trypanosoma_ ), but just an _assassin bug_ , from the Species _Reduvius personatus_. Its common name is masked hunter.
Here is an image of the same bug, also in Ontario, from the Canada Pest Control website:
, have a look at this video from the Smithsonian Channel: <