Ents.
Once, when driving out to Port Townsend (cruising at about 60 mph) I noticed a small branch out of the corner of my eye almost hitting the windshield, and then heard brushing the rear window. I looked in the rearview and there was an alder tree across the road I had just driven on, about 3 feet in diameter. Later that month I read in the paper that a person was killed when a tree randomly fell on them on the Kitsap Peninsula.
Also, would you like to be out in the woods when this puppy snapped?
This thing was about 4-4.5 feet in diameter, and had core rot except the outer foot of the tree: