Sophie Theodora of Castell-Remlingen (12 May 1703, Castell - 8 January 1777, Herrnhut) was a German noblewoman.
By birth she was a member of the House of Castell-Remlingen and by marriage member of the House of Reuss.
She was the sixth child and fourth daughter of Wolfgang Dietrich of Castell-Remlingen by his second wife, Countess Dorothea Renata of Zinzendorf and Pottendorf (1669-1743).
Count Wolfgang Dietrich had fourteen children altogether, of whom Sophie Theodora was the twelfth child and tenth daughter.
On 7 September 1721 she married Heinrich XXIX, Count of Reuss-Ebersdorf, with whom she had thirteen children: