I was more thinking of still in regular service with an airline, rather than a privately owned aircraft which is available for charter.
So was I.
There are DC-3s in airline service in places such as Canada, South Africa, Bolivia, and no doubt others. I know of one DC-3 that is
entering service after extensive refurbishment, this Friday. Scheduled passenger service. (And, of course, there are many airlines all over the world offering 'nostalgia' flightseeing on DC-3s.)
The are Grumman G-21 Gooses (a 1937 design) in service with Pen-Air in Alaska and Pacific Coastal in Canada. Scheduled passenger service.
There are Beech 18s in service in Canada (at least). Scheduled passenger service.
The Ju 52/3ms I mentioned are in service with Swiss airline JU-Air. They often nostalgia sightseeing flights. They don't go from A to B (usually), but they'll take your money to take you up. Isn't that sort of the definition of an airline?