You can find the list of other participants HERE. I'm #155.
The Last Centurian AKA Rory Williams--Rory is one of my very favorite companions EVER. Turning him into a Roman Centurian that stands guard over his wife while she waits in the Pandorica for thousands of years endeared him even more. And then there is this scene. My oldest daughter echoes the words at the beginning--"Coolest scene EVER!" (Oh! and there are Cybermen in the clip too!)
Clara "Souffle Girl" Oswald or "The Impossible Girl". She may have more nicknames than any other companion, but I liked her instantly. It took a while for me to call her anything but souffle girl, but I finally caught on. She first appears in Asylum of the Daleks and she sort of broke my heart with her wittiness, dimples, burnt souffle's and mantra "I'm human!" And of course, we can't leave out "Run, you clever boy." Clara returned to be the Doctor's companion half a series later, giving him the most intriguing puzzle to solve as she died over and over again only for him to find her somewhere else in his time stream.
combination of the Tin Man from Wizard of Oz in appearance and the Borg of Star Trek. Except they've been around longer (I think). Anyway, these creatures start as human, or what ever world has been invaded, and are "upgraded". They have no emotions and view them as a weakness.
Cheem, Trees of--I loved the diversity in the Whoverse. The creativity. This is Jabe, a Tree of Cheem who gives her life to save the Doctor in the episode "The End of the World". Isn't she beautiful!