Perhaps the most common is from a car accident. Of course, there are numerous other motorized vehicles speeding around that get into accidents, either on their own, through the negligence of their driver, or the negligence of a driver in another such vehicle: trucks, motorcycles, boats, snowmobiles, to name a few. With motor vehicle accidents, there is added complexity in Ontario due to parallel claims that are simultaneously pursued: the potential claim for personal injury against the other driver/owner at fault, and the claim for accident benefits with your own insurer.
There are also bicycle accidents, that may, or may not, involve a car insurance component. Personal injury claims also occur following slip and fall accidents. These can be caused by ice, other slippery surfaces, staircases, uneven ground, holes, hazards, even bad shoes. Trip and fall accidents can be due to e.g. carpets, obstacles, bad sidewalks. Chairs can collapse. Items can fall on your head in a store. Decks can break. Some of the other types of personal injury claims are: civil assault (someone beats the crap out of you, causing serious injury); dog, or other animal, bite claims, product liability claims, e.g. an item you bought explodes and injures you.