From the top, Jack Harkness, Martha Jones, Donna Noble, Rose Tyler, and the Doctor.
I've been recently watching it on Netflix, where had this been all my life? Where have I been?? But I haven't gotten to the eleventh Doctor yet, so I didn't include Amy Pond...
As for the cutie marks, I've seen a few Jack ponies where the cutie mark had something to do with his sexuality, which is okay because he's so flirtatious, but I didn't want to play off that, so I poorly attempted the Torchwood symbol. Eh.
Rose is a rose. Clever, yes.
Martha's is a poorly attempted caduceus, for medicine.
As for Donna, it jsut so happens that we dont see it. Hmm. But I think it might be a fireball. Because she's a little ginger spitfire. Lol.
And a side note: The paint was being super derpy with Jack. It bled all over the place. :[ I love Jack. And speaking of Jack, it looksd like Martha's eyeing him up. That wasn't supposed to happen.
Colored with watercolors.
Doctor Who (c) BBC