Richard Wagner’s “The Ring of the Nibelung” is a cycle of four operas, written between 1848 and 1874, loosely based on legends of the Norse gods and the medieval epic “Das Nibelungenlied” (The Song of the Nibelungs). Since you can’t tell the players without a scorecard, here’s a brief roundup of the operas, their characters and the musical themes, or leitmotifs, that describe them.
Das Rheingold: The Rhine Gold (the shortest opera of the cycle, designated as a prelude).
Die Walküre: The Valkyrie
Götterdämmerung: Twilight of the Gods
The Rheinmaidens: Three water sprites, variously depicted as mermaids or Esther Williams clones, who guard the magical gold of the river Rhine, which confers power on anyone willing to renounce love for it.
Alberich: A malign dwarf who, teased and rejected by the Rheinmaidens, curses love, steals their gold, makes it into a ring and promptly subjects all the other dwarves — the Nibelungs — to his will. When the Ring is later stolen from him, he places a curse on it.
Wotan: Father of the gods, used to getting his way. He contracts with two giants, Fasolt and Fafner, to build a castle, Valhalla, in exchange for his sister-in-law Freia; once the castle is built, he goes back on the deal and manages through finagling to give the giants the Niebelungs' gold, and their ring, which he has stolen, in Freia's place.
Fricka: Wotan's much-cuckolded wife, who is always reminding him that the things he wants to do, like trading away her sister in a real estate deal, are simply beyond the pale.
Loge: The half-mortal god of fire, on whom everyone relies and who nobody really trusts.
Erda: Earth goddess, one of Wotan's many lovers, who forecasts his doom and then bears him eight daughters, the Valkyries; they become responsible for gathering up dead heroes and bringing them to Valhalla.
Brünnhilde: Leader of the Valkyries, a warrior maiden, Wotan's favorite and one of the toughest roles to sing in all of opera. Originator of the stereotype of the stout singer in a winged helmet. Eventually defies her father's stated orders so that she can carry out his true wishes, and is punished by being stripped of her divinity and left on a rock surrounded by Loge's fire for a passing hero to claim as his own, the ultimate parental time-out.
Siegmund and Sieglinde: Two human siblings sired by Wotan as part of his plot to get back the ring. They discover each other, and a magic sword called Nothung, in Sieglinde's husband's house and are promptly swept up in passionate and incestuous love.
Siegfried: Son of Siegmund and Sieglinde, raised by Alberich's brother Mime since his mother died in childbirth: the hero Wotan was aiming to create all along. Never having learned fear, he reforges the sword, slays a dragon, claims the Ring, penetrates Brünnhilde's fire and awakens Brünnhilde to his love. (To paraphrase the immortal comedian Anna Russell: "She's actually his aunt. I'm not making this up, you know.")
Gunther: King of the Gibichungs, a race of men. When his half-brother tells him about Brünnhilde, they hatch a plan to claim her for his own.
Hagen: Alberich's son and Gunther's half-brother, scheming to get the Ring back for himself. Plots to drug Siegfried with a magic potion so that Siegfried forgets about Brünnhilde and delivers her to Gunther.
Gutrune: Gunther's hapless sister who is set up to marry Siegfried herself. Unsurprisingly, this love triangle does not end well, and leads to the death of Siegfried, the fall of the gods and the destruction of the entire world while the Rheinmaidens ride in on a tidal wave and seize the ring from Siegfried's blazing funeral pyre as Brünnhilde immolates herself and Valhalla burns in the background.