Tierney is a Celtic surname with a definite Irish twinkle, a name just waiting to be discovered. Though now sometimes used for girls (in the US, not Ireland), as in jazz singer Tierney Sutton, it still has plenty of masculine punch.
Tierney, in its original Tiarnach form, was the name of several saints. It can also join the ranks of Old Hollywood names, via the haunting actress Gene Tierney. ER actress Maura Tierney is a current surname bearer.