20) SARAH JANE SMITH (Elisabeth Sladen, The Sarah Jane Adventures / Doctor Who)
The shrewd investigative journalist of The Sarah Jane Adventures first popped up as the Third Doctor’s assistant in The Time Warrior and went on to accompany the Fourth Doctor on his jaunts. The SJA proved the character was strong enough to warrant a series of her own, and saw Sarah Jane develop a newfound motherly instinct.
19) NUMBER SIX (Tricia Helfer, Battlestar Galactica)
The blonde, leggy Number Six first appears as the Cylon who manipulates Dr. Baltar into stealing secrets that help the Cylons destroy Caprica. After that she appears as Baltar’s sexy, advice-spewing vision, before the introduction of other Sixes who add surprising new dimensions to the character.
18) SUSAN IVANOVA (Claudia Christian, Babylon 5)
Babylon 5’s XO (later Captain, then General) was always a fascinating, multi-layered sort: honest and loyal to her ship and crewmates, often hot-headed but always appealing. In fact, Ivanova was arguably B5’s most engaging human character during its entire run.