My worst was 2006 in my first year of juniors someone skated over the back of my leg after I got knocked down to the ice, completely sliced my left hamstring to the bone. Was able to get back on the ice after about 6 months but the muscle has still never fully recovered.
More recently, few years ago I tore my left groin then a pretty bad sprain again a year later, I've since started taking my pre-game warm-ups way more seriously, stationary bike, stretching, foam-roller, etc... as well as some of Maria Mountain's off-ice groin strengthening workouts and knock on wood have been injury free for a while.