Who Should Be the Next DOCTOR WHO Companion?

Okay, fellow Doctor Who fans...We know that at some point during Series Seven later this fall, the Eleventh Doctor's companions Amy Pond/Williams and Rory Williams/Pond will be leaving both the TARDIS and the television series.  "The final days of the Ponds are coming," current showrunner Steven Moffat has said.  "I'm not telling you when or how, but that story is going to come to a heartbreaking end."

Now, the Ponds/Williamses have had a good run, over two seasons, but the Doctor's next companion is already being discussed even though she (let's face it, probably a she) supposedly hasn't been cast yet.  With that in mind, I started wondering about which female characters we've already met before in previous episodes would make a good replacement companion for Amy...

1.  River Song/Melody "Mels" Pond -- The obvious choice, perhaps, but River Song was such a large focus of Series Six that the show came dangerously close to needing to be retitled River Who.  Although there remains quite a number of gaps in River's history that could be explored, especially as a full-fledged companion travelling with the Doctor, it feels as though most of the main highlights of her story (birth, regeneration, second regeneration, "marriage" to the Doctor, imprisonment, death) have been covered already.  And from a show standpoint, breaking completely away from the Amy/Rory/River saga may freshen the series up in the way Doctor Who needs to do from time to time in order to evolve and grow in new directions.

2. Jeanne-Antoinette Poisson, a.k.a. Reinette, a.k.a. Madame de Pompadour -- Now this is an interesting one.  Most fans, including myself, consider "The Girl in the Fireplace" to be one of the best Doctor Who episodes ever, with an ending so sad and tragic it should never be messed with... unless...  It seems there's been some fan speculation recently of the idea of Reinette returning, after Moffat told his followers on Twitter to follow "Fireplace" actress Sophia Myles -- "Right EVERYBODY who follows me, go and follow @SophiaMyles - spin that fireplace. NOW. I'll explain later. Or not."  Myles tweeted in response, "Watch this (fire)place," and "The plot thickens."  Of course, it's possible that Myles could be brought back as a completely new character, which has been done for other stars such as Freema Agyeman, and not reprise her role of Reinette.

3.  Lady Christina de Souza -- Appearing in the Tenth Doctor story "Planet of the Dead," actress Michelle Ryan portrayed Christina de Souza, a thief of expensive artifacts bored with her aristocratic upbringing.  Several mentions were made during the episode of how well the Doctor and Lady Christina got along, and her thieving skills were proven to be quite useful in adventures.  The character was last seen fleeing from police capture in a flying bus, so it's possible this incarnation of the Doctor may be more inclined to welcome Lady Christina aboard as a regular companion.

4.  Jenny -- Last seen in the Tenth Doctor episode "The Doctor's Daughter," Jenny was a female clone artificially grown from the Doctor's genes.  Although the Doctor believes her to be dead after suffering a fatal gunshot, she later returned to life but did not regenerate and was last shown traveling the universe somewhere in a stolen shuttlecraft.  It should be noted that Jenny was originally slated to die in the episode, but that changed at the suggestion of none other than...Steven Moffat.  Georgia Moffett, who played Jenny, is the daughter of Fifth Doctor Peter Davison and recently married Tenth Doctor David Tennant.  Perhaps she might like the chance to reprise Jenny for a series or two with Eleventh Doctor Matt Smith?