Animate Dead is one of the oldest cards in Magic the Gathering, hearkening back to the days of Alpha, Beta, and Unlimited. It’s been reprinted a number of times: Revised, Fourth Edition, Fifth Edition, as a premium foil in the Graveborn Premium Foil Deck, and most recently in Eternal Masters.
To this day, Animate Dead is still one of the best reanimation spells in the entire game. While a card like Reanimate may only be 1 single black mana, it also has the drawback of losing life. With Animate Dead, you don’t have that drawback.
It’s a powerful little card that finds its way into many Commander decks. In 2017, Animate Dead sees play in 13 percent of the potential Commander decks that run Black on EDHREC. This puts it among the Top 20 Black cards in the format and sees about as much play as Blood Artist and Grave Titan! So, it's in high demand.
In Legacy and Vintage, Animate Dead is outclassed by the single mana Reanimate. But in Commander, it’s still very solid and extremely popular.