Healthy and unhealthy is somewhat a matter of opinion…recommendations change every few years. Fat in any form is to be eaten in moderation as it is also very high calorie. Exceptions of course for athletes who need the calories.
High fat items that I know of:
Butter and oil or any kind (100 cal / Tablespoon)
Nuts, walnuts especially
Nut butters
Avocado
Full fat dairy of any kind
Flax seeds, chia seeds
Olives
Coconut