The first of 'Glee's' 100th episode two-parter airs tonight, March 18, and with it comes six retooled, fan-voted songs. Here's the scoop!

Tonight's episode marks the end of an era for the New Directions, as Jane Lynch's Sue Sylvester finally succeeds in shutting down the glee club. For the landmark ep, almost all of the original characters are coming back, including Heather Morris (Brittany), Harry Shum Jr. (Mike), Mark Salling (Puck), Amber Riley (Mercedes), Dianna Agron (Quinn), Kristin Chenoweth (April), Gwyneth Paltrow (Holly Holliday). Lea Michele (Rachel), Darren Criss (Blaine), Naya Rivera (Santana), Chris Colfer (Kurt), Jenna Ushkowitz (Tina), Kevin McHale (Artie), Chord Overstreet (Sam), and Matthew Morrison (Mr. Shue). Sadly, as we all know, there will be one prominent New Directions member missing: Cory Monteith's Finn.

To hype Gleeks up for the 100th episode, fans got to vote for the 10 songs they wanted to hear in the two-parter. Though all of the songs that will appear in the new episode have been performed in previous episodes, these versions have been revamped. Six of the songs have already leaked online, and they are 'Keep Holding On' featuring Puck, 'Valerie' featuring Santana and Brittany, 'Toxic,' also featuring Britana and Quinn, 'Raise Your Glass' featuring Will (Mr. Shue) and April, 'Defying Gravity' featuring Rachel, Kurt and Mercedes, and  'Happy' featuring Holly, April, Will, Blaine and Mercedes.

The other songs that will be featured in the two-parter are 'Party All the Time' with Holly, 'Total Eclipse of the Heart' with Will and April, 'Loser Like Me' with Blaine, Artie and Tina, 'Be Okay' with Rachel and Santana, 'I Am Changing' with Mercedes and Kurt, 'Just Give Me a Reason' with Quinn and Puck and 'Don't Stop Believin'' with Rachel, Blaine, Kurt, Will, Artie and Tina. Whew!

Listen to 'Keep Holding On'

Listen to 'Valerie'

Listen to 'Defying Gravity'

Listen to 'Raise Your Glass'

Listen to 'Toxic'

Listen to 'Happy'