Ativan is one such drug. They give it out like candy to cancer patients because it supposedly helps nausea of chemotherapy. It also "flattens out" your personality and (supposedly) prevents panic attacks... and is
highly addictive. Which they don't tell you before you take it.
My father had some miserable days after he quit it cold turkey; only after he instituted a 5-week taper did he get a reasonably tolerable withdrawal.