Millennium is a crossover event published in 1987. The core storyline was an eight-issue miniseries written by Steve Englehart, with illustrations by Joe Staton. Every ongoing series being published at the time received crossover tie-ins to the event.
The story involves a Guardian and Zamaron visiting Earth to start the next wave of human evolution. Ten humans are chosen to advance and become immortals, given special powers. They are attacked by Manhunter agents, part of an alien conspiracy posing as close friends and relatives to every single superhero. Eventually this new breed of heroes become the New Guardians.
Having previously left to repopulate their species', Herupa Hando Hu and Nadia Safir return to Earth. They call a meeting of the superheroes, and announce that Earth will be home to the universe's next immortal race. These immortals will be among ten "chosen" people whom the superheroes must protect from their enemies. The Manhunter Grandmaster calls a meeting of their secret cult, announcing that they will reveal themselves to attack the "chosen." These agents include Dirk Davis, Harry Hadley, Lana Lang, Marcie Cooper, Mary Francis Cassidy, Mr. Smith and Rudy West. Tom Kalmaku is caught spying on their meeting, then beaten and left for dead.
The humans chosen by Herupa and Nadia include Betty Clawman, Takeo Yakata, Harbinger, Xiang Po, Nikolai Latikov, Celia Windward, Salima Baranizar, Janwillem Kroef, Gregoria de la Vega, Tom Kalmaku and the Floronic Man. It's revealed that the Manhunters learned everyone's secret identity through access to Harbinger's archives.
President Reagan comes out in support of the heroes on television, a reversal of his criticism during Legends. Salima Baranizar is stoned to death by a mob. Nikolai Latikov is executed by secret police. The Outsiders protect Takeo Yakata, Infinity Inc. protects Betty Clawman, the Justice League protect Celia Windward, Wonder Woman protects Janwillem Kroef, The Flash protects Gregorio de la Vega and the Green Lanterns protect Xiang Po. Harbinger is captured on the Manhunter homeworld. Floronic Man is released from Arkham Asylum by a Manhunter agent.
Herupa and Nadia take the chosen to learn their cosmic secrets. Batman traces the Manhunters back to their headquarters in a Louisiana swamp. Booster Gold infiltrates their ranks by pretending to defect. John Economos sends the Suicide Squad on a search-and-destroy mission. Madame Xanadu helps the Spectre find their location after she is attacked. Floronic Man is influenced by the Manhunters to betray his peers.
Manhunter base is destroyed in Louisiana, their Sonic Temple, removing the threat from Earth. The chosen learn the secrets of the universe. Harbinger escapes with the help of Driq. The League decides to end them once and for all by attacking Orinda, the Manhunter homeworld.
The heroes fight against Highmaster, the mother of all Manhunters. It escapes and swears to hunt down the Oans. Doctor Fate transports them to another dimension, but only Superman and Green Lantern can function there. Booster Gold fights Batman and Guy Gardner as a traitor. The chosen awake from their transcendental state, and Kroef refuses to continue as they conflict with his racist ideals. Floronic Man is swayed by their ideals, and turns to the side of good. Blue Beetle discovers that the Manhunters have a last secret headquarters underneath the Earth's surface.
Fate takes his team back to Earth, and Harbinger returns with them. Herupa and Nadia finish teaching their pupils. The heroes track down the Manhunter underground base, and have a final battle with the androids. It's climactic and explosive, but they take all of them down with no casualties. Booster Gold stops them from destroying the planet with a bomb, but is still taken in for treason.
Finally, the chosen receive their powers. Xiang becomes Gloss, Takeo becomes RAM, Gregorio becomes Extrano, Celia becomes Jet and Betty Clawman becomes one with the planet. Floronic Man decides to keep his own powers, taking the name Floro. Tom Kalmaku also declines, but receives his powers in a latent form for protection. Harbinger has her destiny as one of the chosen revealed to her. Kroef swears revenge back in his own country. Now that the Millennium has come, the other heroes say farewell and leave the chosen to their destiny.