Red vs. Blue
Cinedigm Entertainment; IMDb; official website; RvB Wiki; TV Tropes; Wikipedia; YouTube

This began in 2003, and as of 2018, it's still making new seasons. It's probably one of the earliest webseries I was ever aware of. I know some of my cousins were fans, back in the day, but I can't remember if they were the ones who first introduced me to it, or if I'd already been aware of it, or what. All I know is that I never watched much of it, but it was amusing. And someday I might like to try to watch the whole series from the beginnng. Oh, and it's possible this is the first example of machinima I was ever aware of, I'm not sure. I do think I may have seen some machnima music videos or something, either before or after this, which I wouldn't remember now. But to be honest, I'm not that familiar with the filmmaking style, and I've probably gone entire years without the word "machinima" ever entering my mind.