Click through our gallery to find out who's changed and who's stayed the same:
If you head over to the celebrity section of the site you can also see Madonna dancing with her friends, Jake Gyllenhaal being kissed by his classmates (and wearing what looks like a baby bonnet), Justin Timberlake with freaking enormous hair and a selection of pics of Matthew Morrison that neatly anticipate his starring role in Glee. You can probably also look up your old schoolfriends and relatives or something.
Sidenote: Turns out Sean Penn was prettier in high school than we were. Sadface.
Would you have recognised them all? Let us know in the comments.