A Romulan time traveler who tried to prevent the Federation's founding by killing the young Khan Noonien Singh.
Sera was a Romulan agent who traveled back in time to change human history. Her interference created a dark alternate timeline in which Earth was ravaged by war and James T. Kirk captained an Enterprise that had never known the Federation. She was played by Adelaide Kane.
In 2020s Toronto, La'an Noonien-Singh and the alternate Kirk tracked her to the eugenics lab where the boy Khan was being raised. Sera intended to kill Khan and prevent the Eugenics Wars, which would keep humanity from the path toward unity. She killed Kirk, and La'an killed her in turn, saving Khan and restoring history.