Mariska Hargitay first appeared on ER as Cynthia Hooper before landing her iconic role on Law & Order: Svu as Olivia Benson. Hargitay's persistence in auditioning for ER paid off, as she was initially rejected but later offered the role. Hargitay's portrayal of Cynthia in ER demonstrated a different side of her acting abilities compared to her role as Olivia Benson.

Viewers may not remember, but Mariska Hargitay appeared in ER before her career-defining run on Law & Order: Svu. Throughout 15 seasons of ER, the long-running medical drama has featured numerous main, supporting, recurring, and guest characters filling the ranks of Cook County General Hospital in Chicago, Illinois. While there have been plenty of notable actors to appear as one-time patients, doctors, and other peripheral characters, few have jumped from ER to starring in one of the longest-running TV shows of all time.

Before ER, Hargitay was a relative unknown,...