Yes, tons of them. I have two definitions of underrated:
Names that have never been in the US top 1000:
Ajax,
Andromeda,
Annabeth,
Bellatrix,
Emeric,
Estera, Lunaria,
Phaedra,
Saskia,
Sephora,
Xanthe,
Xerxes,
Zenaida
Names that are no longer in the US top 1000:
Calista,
Carissa,
Casimir,
Casper,
Charlene,
Clarence,
Isadore,
Jada,
Jillian,
Jodi,
Felicia,
Francine,
Linnea,
Marissa, Rhianna/Rianna, Roxy/Roxana,
Sophronia, Twila/Twyla, Zada,
Zenobia