One of the holy women present at the Crucifixion, and who visited the tomb on the morning of the Resurrection (Mark 15:40; 16:1). In Mark 15:40, we read: "And there were also women looking on afar off: among whom was Mary Magdalen, and Mary the Mother of James the Less and of Joseph, and Salome." The parallel passage of Matthew reads thus: "Among whom was Mary Magdalen, and Mary the mother of James and Joseph, and the mother of the sons of Zebedee" (Matthew 27:56). Comparison of the two gives a well-grounded probability that the Salome of the former is identical with the mother of the sons of Zebedee in the latter, who is mentioned also in Matthew 20:20 sq., in connection with the petition in favour of her sons. Beyond these references in the Gospel narrative and what may be inferred from them nothing is known of Salome, though some writers conjecture more or less plausibly that she is the sister of the Blessed Virgin mentioned in John 19:25.
(Taken from Catholic Encyclopedia)