The character of River Song is an interesting one in the Doctor Who mythos. Like the Doctor, her history isn’t linear because of time-travel and she has met up with multiple incarnations over the years. Originally being introduced opposite of David Tennant, getting lots of time with Matt Smith and even sharing a long evening with Peter Capaldi. But whose to say those are the only Doctors she has adventured with?
BigFinish Audio is doing a series of stories with Kingston called the Diary of River Song and they’ve done up an almost James Bond-style trailer for the second series which will include the voices of Colin Baker and Sylvester McCoy, the sixth and seventh doctors. While the first series featured Paul McGann, the Eight Doctor. If this continues, maybe they’ll get Tom Baker or Christopher Eccelston.