Board Thread:The Panopticon/@comment-24070818-20131124143458/@comment-26975268-20131124161135

Of course, this would also make Craig Owens part of the primary cast of s6, even though he only appeared in one episode.

So, alternatively, we can use number of appearances in the season. If they appear in three or more episodes, they're primary.

So:
 * Eleventh Doctor
 * Amy Pond
 * Rory Williams
 * Clara Oswald
 * Vastra
 * Jenny
 * Strax
 * Great Intelligence/Walter Simeon