Although earlier sets contained autograph cards, cards hand signed by celebrities related to the set in question, they started to become more common when SkyBox inserted original series signatures, at a ratio of one per box, in the Star Trek: The Original Series set issues in 1997.
Some manufacturers have used such variations as dual autographs, triple autographs (and more!), autographed memorabilia cards and cut autographs, where a signature from a check or other document is secured into a specially produced card.