In 'Hannah Montana' series which alter ego did Miley Stewart have by night?

Hannah Montana, also known as Hannah Montana Forever in its fourth and final season, is an American musical comedy television series created by Michael Poryes, Rich Correll, and Barry O'Brien. It focuses on Miley Stewart (portrayed by Miley Cyrus), who is a teenager living a double life as an average schoolgirl by day and as the famous recording artist Hannah Montana by night, which she keeps secret with only a few people knowing of her alter ego. The story follows the daily life of Stewart, her brother Jackson, her best friends Lily and Oliver, and her father Robby (Cyrus's real-life country singer father, Billy Ray Cyrus).

The series, produced by It's a Laugh Productions and Michael Poryes Productions, premiered on Disney Channel on March 24, 2006, garnering 5.4 million views, giving the Disney Channel the highest ratings in its history at the time and concluded on January 16, 2011, after having aired four seasons and ninety-eight episodes.