Justis Bolding
From Halopedia, the Halo wiki
Justis Bolding is an American actress who voiced the character Miranda Keyes for Halo 3, replacing Halo 2's Julie Benz, notably because Bungie wanted someone with more of an accent than Benz. She also plays the role of Sarah Robertson, the ABC daytime soap opera One Life to Live.
Bolding has a degree from Muhlenberg College and has previously appeared on the American TV series 7th Heaven (2005) and Undressed (2002).