There are so many reasons to love Gilmore Girls, but easily one of the best parts of the show was its incredible cast. Even beyond Lauren Graham, Alexis Bledel, Kelly Bishop, Melissa McCarthy, Scott Patterson, Keiko Agena, and the rest of the Stars Hollow crew, the series had an impressive roster of supporting players and guest stars — many of whom would go on to become big stars in their own right in the 20 years since Gilmore Girls premiered. 

Click ahead to look back on 19 stars who appeared on Gilmore Girls before they were famous, including actors from Parks and Recreation, Timeless, The O.C., The Vampire Diaries, and Mad Men.

Before Hamm was the slick Don Draper on Mad Men, he was one of the worst dates Lorelai had ever been out with. Hamm appeared in a Season 3 episode as Peyton Sanders, the handsome son of one of Emily's friends, which meant that even though Lorelai hated every second of their date, she gets guilted into a second one to appease her mother. Unfortunately, Lorelai and Peyton's trip to see David Bowie all happened off-screen and he was never seen again.

On One Tree Hill, Murray might have played the kid from the wrong side of the tracks, but on Gilmore Girls, his character's family probably owned the tracks and the entire train line. For two seasons, Murray played Rory's Chilton classmate, Tristan, who expressed his feelings for Rory by constantly mocking her and insulting her boyfriend Dean.

Long before he was the gruff mentor of Leslie Knope on Parks and Recreation, Offerman was the gruff brother of Jackson on Gilmore Girls. The actor appeared in two episodes as Beau Belleville.

The same year Lynch starred in the mockumentary Best in Show, she also appeared as a nurse who gets harassed by Emily when Richard is hospitalized in Season 1.

In between her roles on Veronica Mars and Breaking Bad, Ritter played Rory's friend, Lucy, on Gilmore Girls' final season.

We rarely saw much of Lane's life at the Seventh-day Adventist college. Otherwise, we would have gotten many more scenes with the Mr. Robot star, whose first acting job was playing Lane's classmate with an odd obsession with assistant pastor Eric.

We like to imagine that in an alternate universe Brody stayed on Gilmore Girls as Lane's lovable boyfriend Dave Rygalski. Unfortunately, in the real world Brody left the show for The O.C. after Gilmore Girls Season 3 and Dave left Stars Hollow for -- you guessed it -- California.

The former Nickelodeon star made her onscreen debut as a young attendee at a Lord of the Rings-themed birthday party that Lorelai and Sookie catered. Justice's character wasn't a fan of Sookie's elaborate spread, leading to a hilarious face-off between the duo that ended in tears for one and a major existential crisis for the other.

Years before Greenfield appeared on Veronica Mars, the New Girl actor played a drunken attendee at Dean's bachelor party who attempted to bond with Luke over sharing the same name.

You know this hilariously talented comedienne as one half of Garfunkel & Oates. Before her comic duo days, she appeared in Seasons 3, 5, and 6 of Gilmore Girls as Juliet.

Pedrad only had a few credits to her name before she landed Saturday Night Live. One of those was the role of a waitress who served a very drunk and a very sad Rory in Season 6.

Melissa McCarthy's husband appeared on Season 3 of Gilmore Girls as Mr. Brink, the executor of Fran's will. Falcone has since starred in many films, including Bridesmaids, alongside McCarthy.

Not only did Gilmore Girls land The Bangles for the Season 1 episode "Concert Interruptus," but the show also landed the future Superman. The Superman Returns and Legends of Tomorrow actor played a hottie at a Bangles concert who convinced Madeline and Louise to ditch the show and come to a party with him, much to Lorelai's chagrin.

The Community star appeared in four episodes as Raj, a Yale Daily News writer during Rory's stint as editor. 

The John Tucker Must Die and Vampire Diaries actor played Lindsay, Dean's wife, on Gilmore Girls. 

The Family Guy creator played one of Lorelai's obnoxious business school classmates who judged Lorelai harshly for coming from money. He also voiced Emily's lawyer in a Season 3 episode, but was never seen onscreen in that role.

The Heroes star had a minor role as a Harvard student who debates relativism with Rory when she sneaks into a class in Season 2.

In his very first TV role, Jones played Morgan, who cheered on Jackson as he fried a turkey for Thanksgiving. He'd go on to bigger small screen roles on Breaking Bad and Mom.

This Timeless and Suits star had a brief part during Gilmore Girls' sixth season.