Who would win in a fight between a grizzly bear and a lion?

Assuming that they fought (the two have no common ecological habitats), either could win.

The bear is much heavier and stronger, and has sharp, deadly claws. However, the lion is more agile and a large lion could possibly kill a bear if it inflicted injury to the bear's neck. There are instances of a wolf pack killing a bear in this way.

There are records of Siberian tigers, a cat somewhat larger than lions, killing brown bears.