See our picks below.
(Season 1, Episode 13)
The New Directions are crowned winners at their first sectionals -- but not without plenty of chaos and drama. After Finn (Cory Monteith) discovers his best friend Puck (Mark Salling) is actually the father of girlfriend Quinn’s (Dianna Agron) baby, he abandons the glee club right before the big competition. The group arrives to sectionals to find out their competitors have taken their three chosen songs, leaving the club no choice but to improvise a new setlist. Finn returns and the New Directions deliver a show-stopping performance, with Rachel (Lea Michele) belting her hair-raising rendition of Barbra Streisand's Funny Girl standout "Don't Rain on My Parade" before the group’s cover of the Rolling Stones’ "You Can't Always Get What You Want.”
“The Power of Madonna”
(Season 1, Episode 15)
The episode opens with cheerleading coach Sue (Jane Lynch) declaring her love for Madonna, whom she calls “the most powerful woman to ever walk the face of the earth.” Sue and glee club coach Will (Matthew Morrison) challenge the cheerleading squad and the glee club respectively to channel their inner Madonna, with Will hoping to empower New Directions' female members. Madonna granted Glee full access to her catalog for the episode and the cast took full advantage; the episode is packed with hits by the Queen of Pop, including “Express Yourself,” “Like a Virgin” and “Like a Prayer.”
(Season 2, Episode 2)
Cheerleader Brittany (Heather Morris) finds herself in the spotlight for this tribute episode to Britney Spears. Brittany -- who reveals her full name as Brittany S. Pierce -- reveals she has lived in Spears’ “shadow” her entire life and discourages the glee club from performing the pop star’s music. However, after she is put under anesthesia at the dentist, Brittany experiences "Britney hallucinations" set to some of Spears’ biggest hits. While the episode has been criticized for lacking in plot, there’s something to be said for Brittany’s killer “I'm a Slave 4 U” performance; the former Beyoncé backup dancer recreates some of Spears’ most iconic dance moves and looks, and pulls them off almost too convincingly.
(Season 2, Episode 3)
Glee tackles the sensitive topic of religion in this episode, as Kurt (Chris Colfer) struggles after his dad suffers a heart attack and Finn believes he’s found the face of Jesus in a grilled cheese. “Grilled Cheesus” strikes the perfect balance of comedy and seriousness, portraying a wide spectrum of religious views among its cast. The episode featured seven cover songs -- including "I Want to Hold Your Hand," "Only the Good Die Young" and "Losing My Religion" -- which all charted on the Hot 100.
"Blame It On the Alcohol"
(Season 2, Episode 14)
The episode mainly focuses on underage drinking as Rachel throws a party the same week the glee club is slated to perform at an assembly about the dangers of alcohol. At the party, Rachel and Blaine (Darren Criss) share a drunken kiss before performing a karaoke duet to The Human League's “Don’t You Want Me.” The next day, the hungover high schoolers attempt to feign normalcy while they attend classes and later perform Kesha’s “Tik Tok” at the assembly.
"The First Time"
(Season 3, Episode 5)
“The First Time” somehow manages to weave together two very different storylines: McKinley High gearing up for its production of West Side Story and Glee's two couples -- Rachel and Finn, and Blaine and Kurt -- deciding to lose their virginity. The expertly crafted episode mainly features West Side Story classics like “Tonight” and “America,” but also includes a catchy cover of Billy Joel’s “Uptown Girl” sung by the Dalton Academy Warblers.
"Dance With Somebody"
(Season 3, Episode 17)
New Directions grapple with the death of Whitney Houston, opening the episode with a moving rendition of "How Will I Know" as they pass around a framed photo of Houston in the halls. The episode was shot shortly after the powerhouse singer's passing in early 2012 and paid her tribute with the glee club jamming out to "I Wanna Dance With Somebody," Rachel and Santana (Naya Rivera) delivering the high energy "So Emotional" and the group coming together onstage to close with "My Love Is Your Love."
(Season 3, Episode 21)
Glee fans waited three years for the day New Directions would get their shot at Nationals and this episode delivered. The club faces off against Vocal Adrenaline and delivers some of their most spectacular musical numbers yet, earning a standing ovation and roars of applause with their last song, "Paradise by the Dashboard Light." "Nationals" might've been a little predictable, but it gave the fans everything they wanted and more; after all, who doesn't love a good underdog story?
"The Break Up"
(Season 4, Episode 4)
The episode is aptly titled "The Break Up" for a reason, and few of Glee's power couples go unscathed. Finn reunites with Rachel but feels without purpose after being discharged from the army, while Blaine feels neglected by Kurt who's caught up in his new job at Vogue. In the end, both couples decide to call it quits, along with Brittany and Santana who struggle with their long-distance relationship.
“You are my first love and I want more than anything for you to be my last, but I can’t do this anymore," Rachel tells Finn. The two share a last kiss, and all of the show's couples perform a heartbreaking rendition of Coldplay's "The Scientist" as flashbacks from their relationships roll. Cue the waterworks.
(Season 5, Episode 3)
Cory Monteith, who played Finn, died tragically of a drug overdose in July 2013 and "The Quarterback" was dedicated to him. The episode opens with new and old members of New Directions joining together to sing "Seasons of Love" from Rent at Finn's funeral, and follows the cast mourning his death and coping with their grief in very different ways. The characters' song tributes to Finn are heartbreaking to watch -- notably, Rachel's flawless performance of Bob Dylan's "Make You Feel My Love" -- but the episode is beautifully executed and fused with powerful, raw emotion.