Board Thread:The Reference Desk/@comment-95.172.232.188-20140404191002/@comment-4139960-20140404205402

Technically Billie Piper, I suppose. With Eccleston as Rose; with Tennant as both Rose and the Moment at different points; and with John Hurt and Matt Smith as the Moment.

Counting spin-offs, Elisabeth Sladen's appeared opposite Pertwee, Tom Baker, Tennant and Smith. (School Reunion might not have counted a starring appearance, but I'm sure The Wedding of Sarah Jane Smith does.

Jenna Coleman, who appeared with the Hurt, Tennant and Smith (and if you count the Curator as a Doctor, Tom Baker) in The Day of the Doctor, and also appeared with other actors using repurposed footage in The Name of the Doctor.

Nicholas Briggs as a Dalek voice actor and Barnaby Edwards and Nicholas Pegg as Dalek Operators, all of whom have been working since the Eccleston era, and counting Big Finish, Briggs has had even more appearances alongside the "classic" Doctors.