From the pilot episode, it seems like Alison DiLaurentis is the main character on Pretty Little Liars. When she went missing, she was the leader of her friends, and everyone in Rosewood was obsessed with solving the mystery.
Hanna Marin was another major player on the teen show, as she was part of Ali’s social circle and was targeted by A as soon as Ali went missing. Popular for her fashion sense, wit, and long-term relationship, Hanna can be viewed as the main character on PLL for several reasons, including some of the trouble that she often found herself in.
Mona was behind a lot of mean things on the show and when Ali disappeared, Mona and Hanna became super close. They dreamed of being popular and with makeovers complete, they almost took over where Ali left off, although they didn’t seem to be so cruel.
Since Hanna was best friends with Mona, who was the first A, that suggests Hanna can be viewed as the main character. She was the character who interacted with Mona the most, and this was very helpful, as the girls wanted to know as much about Mona as they could find out.
Hanna could have dated many characters, but she was pulled into Caleb’s orbit and they never really left each other, even when they weren’t together.
Hanna and Caleb have so many elements of a classic love story on a teen drama. They snuck around at first and Hanna even had Caleb secretly live with her because he didn’t have a place to go. They were serious about each other even when they didn’t know each other that well and while they did break up for a while, they never fell out of love. They dealt with everything from sex to Caleb moving away to the personal struggles that they both had.
One of the major storylines in the early seasons of Pretty Little Liars was Hanna’s shoplifting. This got her in hot water with Detective Wilden, and when her mom slept with him to save her from consequences, Wilden became even more suspicious of the liars.
Wilden wondered if Hanna and her friends were behind Ali’s murder, and he seemed to dislike Hanna the most. The fact that Wilden considered her such an important piece of the puzzle points to her being the main character. She definitely always got a lot of attention.