I was, for the most part, created to accompany something else. It would seem like I'm just playing second fiddle to a jive-talking glory hog, but that's not actually the case; we both wound up being really famous and respected. In fact, I'm arguably more famous than my master, because I get around more--I'm more versatile and less likely to get in the way of people, and I don't need as much gas to get to the same place.
But now it's all right, it's okay; we'll live to see another day. As of fairly recently (well after Stack Overflow was founded), both myself and my master are currently being preserved by a very powerful organization for all of time. We'll both be stayin' alive for a very long time, which is more than can be said of the three men to whom I most owe my existence. It's a shame that two of them are dead, as we really had a great thing going on; if I can't have them, I don't want nobody else. The oldest guy is still around, at least, but it just doesn't feel the same without his brothers, too.
Apparently, the three guys who made me originally worked with three others for a little while, though this was before my time. They also had a younger brother who did his own separate thing, but I never met him (and he's dead too, apparently).
Also, who's taller, my master or me? Well, that's actually an interesting question. It depends on whether or not he's allowed to show you his penis. Yes, really. Though I suppose it doesn't really matter anyway, because we're both about the same height regardless.
Finally, not that it matters much to me, but everyone generally likes to pretend my master's little brother doesn't exist.
Hints
It's a very specific thing. A famous thing.
It's older than I am, but I don't know if it's older than you (StackExchange attracts a pretty wide audience these days).
If you tried to sell one of these without getting permission from a different large organization, they would get very mad and might sue you.