Bessan people

As Brother Lassar disclosed whilst speaking with the Tenth Doctor, the people of Bessan had "some rather lovely wings". Ten generations prior to 2007, Bessan was invaded by the Krillitanes, with Lassar recalling that Bessan made a million widows in one day. The Krillitanes adapted the wings of the Bessan people to assume a bat form. (TV: School Reunion)