Unless you've been living under a rock somewhere -- completely safe from millennials and each and every form of social media -- you should have heard something about Disney Channel's upcoming summer movie marathon featuring all 99 Disney Channel Original Movies (DCOMs for short), in honor of the release of the 100th one later this year. The marathon will begin over Memorial Day weekend with the 51 most popular DCOMs airing first, and the remaining movies will be shown sporadically throughout the month of June. For most, this is one of the best things Disney has done in a while, seeing as the DCOM is a staple of many a millennial's childhood. Aside from a slightly important oversight on Disney's part, this summer's schedule is packed with some excellent titles from your youth, such as "Smart House" (1999), "Cadet Kelly" (2002), and, of course, the timeless classic: "The Cheetah Girls" (2003).

You can check out the entire summer line up right here, but before you start marking your calendar to catch your faves, perhaps a stroll down memory lane is in order? I know, it's been a while since a lot of these were released, but there are a lot of familiar faces you might have forgotten were once a part of the DCOM family. Have a look below at some of the A-List stars of modern Hollywood that were once doing their thing on the silver screen, and don't forget to add their work to your marathoning to-do list!

1. Justin Timberlake, "Model Behavior" (2000)

In the video above, check out baby JT in the prime of his youth (At only 18! What a cutie!) in an interview about "Model Behavior," the DCOM he was in back in 2000. It was the peak of NSYNC's career, and Justin was certainly an apt choice for this film, playing the hunky male-model boyfriend in this coming-of-age tale about swapped identities, following your dreams, and dealing with hardcore parental pressure. Although it wont be featured during the Memorial Day weekend marathon, you should definitely still check this one out!

2. Katherine Heigl, "Wish Upon A Star" (1996)

Talk about retro -- just look at that fashion! In this light-hearted comedy, Heigl plays Alexia Wheaton, the typical "popular" girl in school who has it all: the clothes, the look, and the most popular boy in school wrapped around her finger. Everything changes when her little sister makes a wish on a shooting star and they swap bodies, As the trailer above states, "The world looks a whole lot different when you see it through someone else's eyes." Unfortunately, this movie also isn't a part of the holiday weekend marathon, but catch it on Disney Channel sometime in June -- it's one of the most underrated DCOM's out there!

3. Bryan Cranston, "'Twas the Night" (2001)

Though you may not recognize him with a full head of hair (a far cry from his signature "Breaking Bad" look), Cranston was once the star of a holiday-themed DCOM about a man who learns the importance of honesty, selflessness, and the love of your family. Sure, it may not be at the top of anyone's "nice" list, but this heart-warming holiday movie is nowhere deserving of any coal, so check it out in June if you want to see Walter White in a Santa suit!

4. Brie Larson, "Right on Track" (2003)

This DCOM is based on a true story about two young sisters who face numerous obstacles in the male-dominated sport of drag racing. Check out the Oscar-winning Larson at 0:45 in the video above, where the most-recent Best Actress can be seen sporting a very dated (but still adorable) aesthetic. You can catch "Right on Track" on Sunday, May 29th, scheduled to air at 6:00 am on Disney.

5. Kristen Stewart, "The Thirteenth Year" (1999)

By far one of the best DCOM'S ever, "The Thirteenth Year" is a classic story of growth and transformation during one of life's greatest periods of uncertainty: puberty. Kristen Stewart had a blink-and-you'll-miss-it part (as seen above), and though she was originally uncredited for the role, it is now listed on her IMDB page as her first acting appearance. You can watch the fishy tale that is "The Thirteenth Year" on Saturday, May 28th, rather unfortunately scheduled to air at 4:20 A.M.

6. America Ferrara, "Gotta Kick It Up" (2002)

Before she was Ugly Betty, Ferrara got her start playing a young cheerleader in this DCOM based on a true story about a middle school dance team. This film, centered on a dance troupe of young Latina girls, focusing on the friendships, hardships, and social pressures they faced, and the societal obstacles they worked to overcome by following their passions. Sadly, this film also won't be a part of the Memorial Day weekend marathon, but you should definitely DVR for this one when it airs in June!

7. Taran Killam, "Stuck in the Suburbs" (2004)

Best known as one of Saturday Night Live's most versatile cast members in recent years, Killam was once teenage heartthrob "Jordan Cahill" in one of Disney's first DCOM's to accompanied by its own soundtrack. Don't let those bleached tips fool you -- this memorable DCOM covered all the bases in terms of themes, featuring everything from the difficulties of teenage friendships to the classic Disney message of being true to yourself. As a result of this DCOM's popularity, you can catch this flick at the very reasonable time of 10:00 A.M. on Monday, May 30th.

8. Diane Keaton, "Northern Lights" (1997)

Considered the first official DCOM, this movie is likely one you've never heard of -- the above clip is one of the only pieces of evidence I could find that shows this thing even exists, and you can only see Keaton for a brief flash at the end. But, since this is DCOM royalty, it felt wrong not to include it on this list. This is one of the more adult DCOM's around, dealing with heavy themes of death, mourning, and struggling to fit in. Not surprisingly, this film also isn't a part of the marathon, but will likely be shown on Disney Channel sometime in June.

9. Lindsay Lohan, "Get a Clue" (2002)

Though you may associate her with another Disney classic -- "Life Size," featuring the iconic performance of Tyra Banks -- Lohan starred in this teenage mystery drama alongside Brenda Song (of "The Suite Life" and "The Social Network" fame). This is actually one of my favorite DCOM's, and also has a smattering of recognizable faces (such as Ian Gomez and Amanda Plummer). It's a shame that this DCOM isn't a part of the holiday weekend lineup, but you should join me in making sure to record it when it airs in June!

10. Camilla Belle, "Rip Girls" (2000)

This DCOM has it all -- a super dated soundtrack, conflict and resolution within the context of family, and the exact fashion choices you would expect of a movie made in 2000. Belle stars as Sydney Miller, a 13-year-old girl who returns to her native Hawaii to learn more about her late mother and, in the process of exploring her family's history, learns even more about herself. Make sure to check out this feel-good classic at the prime time of 2:55 P.M. on Sunday, May 29th.

11. Hayden Panettiere, "Tiger Cruise" (2004)

Behold, the beginnings of the Disney-actress-turned-singer phenomenon! Panettiere starred as Maddie Dolan in this military-based DCOM that intertwined the real-life events of the 9/11 attacks with the film's fictional story. This is one of the only two DCOM's that featured a PG-13 rating, but the family values and pretty patriotic messages underlying the film's plot make this DCOM somewhat forgettable in the grand scheme of things. As a result, you can find this one airing on Disney Channel sometime in June after the more popular ones have finished showing during the Memorial Day weekend marathon (although, given the subject matter of this movie, it would seem rather appropriate to show it that weekend instead).

So, how'd you do? Do you remember seeing these celebs before they made it to the big leagues? If you recognized them all, then you truly are a master of the DCOM. And, if not, why not take advantage of the incredible opportunity that Disney is giving us by catching up this summer on all the movies mentioned above and any others you might have missed? If you need a refresher of all the best DCOM's, then check out Entertainment Weekly's ranking of the top 30, but don't let that stop you -- after all, you do have 99 to catch up on before the 100th airs on June 24th at 8:00 P.M!