Bytown is the former name Ottawa, Ontario, Canada.

Located where the Rideau Canal meets the Ottawa River, it took its name from John By, who as Colonel of the Engineers was instrumental in the construction of the canal. Bytown was incorporated in 1850 and upon incorporation into a city in 1855, it was given the new name Ottawa. The part of present-day Ottawa which occupies the original site of Bytown is known as the By Ward Market area of Lower Town. The history of Bytown is covered in the main article on Ottawa.