Grey's Anatomy

Miranda Bailey was the only role written with a character description: "tiny blonde with curls."

The character Alex Karev was not in the original pilot script; his role was inserted into the pilot as an afterthought in order to provide a foil, as well as male companionship for Dr. George O'Malley. Since he wasn't added until after the pilot was shot, scenes with him were either re-shoots or digitally altered.

In order to keep the plot and storylines secret, the main characters' names are changed in auditions.