A powerful monster begins killing people in the area (Tremors: Jaws in a desert).
Win a war.
Lead an army against enemy general, against rival mob boss or a cowboy gang.
The villain is a respected public figure, celebrity, is liked by people or has authority over you.
Tribe/horde of orcs/goblins/kobolds/etc
Maintain the power/status they already possess.
Protect/Escort /Guard a person/creature (a rich merchant, a researcher, a young prince targeted for assassination, a last of its kind monster, tax collector, witness).
Overcome environmental obstacles
A river on your way, a closed gate, climbing a mountain, a swamp, quick sand, slipping hazard above the abyss, thin ice, wild magic area. Retrieve an item from the bottom of the lake.
Find a way to get someone to owe you a favor, find a way to repay the debt you owe to someone else.
Figure out who's behind the plot.
Sneak into the king's chambers, lure them out, use poison, make it look like an accident.
Get your minions into various positions of authority.