Here's a list I've compiled from my own trips! I'm sure as I get more experienced I'll be cutting down on my gear a lot. Very skilled canoeists pack extremely lightly.
A backpack - ideally with waist-level straps and a solid back
Rope - for lifting food up in trees, and other things
Boots with good ankle support, preferably waterproof
A drybag large enough to fit things that must not get wet
A whistle for signalling distress
Towel - I use a small microfibre towel that dries quickly
A wide-brimmed hat that stands up to water
Tent - make sure it's light! If it comes in a big box-bag, NO!
A blow-up mattress to sleep on.
Waterproof flash light
A way to make water potable. You can boil it, filter it, zap it with radiation, etc.
A toothbrush & toothpaste, floss is good to have too
A good-quality map protected from water
Canoe-specific essential things
PFDs for everyone on board
Paddles (obvious, but this is a checklist)
Food Related Essential Things
Mixed nuts for snacking
Breakfast, I like granola that I mix with the above and some water
Lunches, I usually go for peanut butter, a heavy bread, some cheese and smoked meat
A grill for cooking over campfire (arguable, if you rely on a stove)
Aluminium foil for nice mixes of potatoes, vegetables, fungi
A light, durable bowl and cup, along with a sturdy spork
A cooking stove, like a small isopropane one. Rain/no wood? No problem!
Bug net shirt + head cover. They don't take up much space, I rarely use them.
Bug repellent, Muskoil is supposed to be good. I don't really like the stuff, but many do.
Axe/hatchet. I love my lightweight hatchet
A bathing suit - I'm a bit torn on if this is essential or not
A reading light
Some people need chapstick - I've never had a problem without it
Dish soap that is friendlier for the lakes (phosphate free, soil-biodegradable)
Saw - I have a nifty one that comes apart and fits in a small cylinder
volume for water storage, mine is 15 L
garbage bags, if you are going to a managed park they'll probably give you a couple
A large pot
Coffee/tea and minimal accessories
Tarp - you can hide under it outside if it rains