The Day of the Doctor - S7-E16
Other mistake: Billie Piper is listed as playing "Rose" in the closing credits. Rose was certainly mentioned, yes, but Piper in this episode was actually sentient superweapon the Moment, who merely took Rose's form, and was in all other respects nothing like the former companion.
Chosen answer: No, no information is avalible for the identity of the entity.
Repo_Man