GOKAAAAI... SILVER!
Y’know, I’ve always found it interesting that Aquamentus was the first boss of the entire Legend of Zelda franchise… but it’s only appeared in two main series games (not counting the Zelda Game & Watch). Same with Digdogger, another boss from the original game. Both of these bosses reappeared in Oracle of Seasons (since that was originally intended as a remake of the original game, but many of the old bosses remained in the game even after this plan changed), but after that, they never appeared again. Every other boss from the original Zelda has appeared way more than that.