English, French, German and Polish from Latin/Greek for "stranger/foreigner".
Barbara is spelt Barbra - erroneously believed to be a recent "modish" spelling - in a significant proportion of records [over 25%] in the 1841 Census of Aberdeenshire. Other, far less frequent, spellings include Barabra, Barbarah, Barbare, Barbars, Barbraw, Barbray, Barbro and Barbrow.
Pet names and Diminutives occurring more than once include Bar, Barb, and Barba. A correpondent [TL3] has found the use of the pet name Barberie/Barbery is common in The Kingdom of Fife, Scotland.