My job gives me plenty of opportunities to nab a ride on positioning or ferry flights on various big jets for whatever reason, so ZERO pax would be the most accurate answer.

Some of the more memorable ones in the last few months :

Keflavik to Accra nonstop on a 757. There was a delivery flight planned for a wingletted 757 to go down on a lease, so I called a friend and arranged a ride. Just myself, the two pilots (both old friends of mine) and two engineers (another old friend) on board for the 8h37m trip. Fantastic departure from Keflavik into the winter evening with the Northern Lights visible from the cockpit. Landed in Ghana just after dawn and proceeded to catch a flight back to London at 730am!

Paris CDG to London Gatwick on a 767. We had just spent a long day running charters and got back into Paris from Marrakesh well after midnight. The cabin crew were out of hours but the pilots had some time left, so we decided to continue and ferry the plane back to London right then for her next rotation later in the morning. Just myself and the 6 girls in the cabin for the 22 minute flight in the middle of the night - we spent more time taxiing than we did in the air. Lots of fun stuff (amazing what you can cram in to 22 minutes) that can't really be discussed on a public forum that the CAA might one day read!!!

Lagos to Accra to London Gatwick on a 757. A plane went tech in London so we were chartered in to provide a rescue flight. Full load from London to Lagos, but the return was planned to be a ferry flight. Unfortunately, since the relief crew couldn't get Nigerian visas on short notice, we had to reposition to Accra for crew change and the charterer took the opportunity to place about a dozen revenue passengers on board and make the leg live. I was absolutely exhausted having flown for almost 24 hours without a break, so I just stretched out across a row and was woken up 7 hours later when we were on final approach.

Bridgetown to Accra on a 757. Repositioning an aircraft after a charter from Sierra Leone to Barbados with just the crew on board. A beautiful dawn departure from Bridgetown over spotless beaches and azure waters led to a long flight over water with no land in sight until we hit the coast of Liberia about 6 hours into the 7h42m trip. Ironically due to solar interference we couldn't reach Dakar Oceanic on HF but were able to communicate fine with Gander Oceanic, creating a rather strange ATC situation. Fortunately there was no traffic within 1000 miles of us (nothing that could make it up to FL410 anyway!) and we managed to establish contact with Cape Verde on VHF once we were closer in.