Black Waltz 1 is a boss from Final Fantasy IX. It catches up with the party on the trek through the Ice Cavern, and casts a Blizzard spell, which puts the entire party to sleep. Zidane is for some reason slightly resistant to this spell and confronts the Black Waltz alone.
After the battle, Zorn and Thorn (as disembodied voices, and are then seen moments afterwards) warn Zidane that No. 2 and 3 will take No. 1's place.
Why didn't you fall asleep? You should be dead by now...
At the start of the battle, Black Waltz 1 summons a Sealion to assist in defeating Zidane. The Black Waltz's only attacks are Blizzard and Fire. If its accompanying Sealion is ever below full health, the Black Waltz will target it with Blizzard, healing it. Because Zidane is fighting alone, it is easy for Trance to activate, and his Dyne attacks can kill the Black Waltz with ease.