Siobhan

Siobhan is the unaccented spelling of Irish Siobhán, a form of Joan that came through the medieval French name Jehanne. Its wider family reaches back to the Hebrew name behind John, traditionally understood as God is gracious. The bh spelling reflects Irish sound conventions, which explains why the name is not pronounced by reading each letter as English.

Actress Siobhán McKenna helped make the name internationally recognizable, and modern fiction has added further bearers, including Siobhan Roy in Succession. The nickname Shiv in that series follows the opening sound. Sinéad is related through the broader John family but is not simply another nickname for Siobhan. Families choosing it can retain a distinct Irish form while sharing a meaningful connection with relatives named Joan or John.