Opossums
Facts: Opossums are all bark and no bite. If confronted, they will try to run. If there isn't a way out, they will open their mouth and hiss while showing all 50 of their teeth. As a last resort, they will fall over and play dead. They will also look drunk by swaying and drooling, which is often mistaken for rabies. They are diaurnal meaning they can be active day or night. They are natures exterminator eating bugs, snakes, mice and the occasional rat.
Problem:
Rabid behavior: While not impossible, rabies has never been confirmed in opossums due to their low body temperate making it hard for the virus to survive long. The behavior most see is actually defensive behavior.
Lone baby: Opossums are marsupials meaning they give birth in a pouch, just like a kangaroo. After about 2.5 months, they will emerge and ride on moms back. The occasional one will fall off. The rule of thumb is if it is 7 inches or more (not including the tail) it is old enough to be on it's own. If under 7 inches, call your local animal control or rehab for assistance.
Opossum in/around the garbage- Like other wildlife, opossums won't turn down a free meal. Simple garbage/compost management will prevent this (tight closing container, not composting meat, eggs, fats, etc)
Opossum stuck: First ensure it is truly stuck. A scared opossum will freeze for several minutes after being scared. If it is stuck in a window well/egress window, place a large stick or 2x4 at an angle and check in the morning. Place a cover over it to prevent repeat falls. If it is stuck in a spot it needs to be handled to unstick, call your local police, animal control or rehab for assistance
Dead Opossum: Make sure it is dead. Opossums will play dead as a defence mechanism. While slowed, you will still be able to see it breathing. If it is truly dead and it is spring or summer, check the pouch. Opossum babies are "born" as very small embryos into the pouch and latch on to mom. While they can be hard to remove, they can be unscrewed by slightly rotating them. Get them to a rehab ASAP. If you are not comfortable checking the pouch, call your local rehab or animal control for assistance.