Christina Tom (The Bells of Saint John)

Christina Tom was an employee of Miss Kizlet whose Twitter was found by Clara Oswald using face-match. She used this information to discover where Kizlet's offices were.

On the orders of the Great Intelligence, Miss Kizlet reset her and all other employees to factory settings, and they returned to their true selves. (TV: The Bells of Saint John)

Behind the scenes
The Twitter profile was based on the episode's graphic artist Christina Tom. (DWMSE 37)