Guardians of the Globe

 Mr. Martian (Top left), Darkwing, Red Rush,
Aquarus, War Woman,  Green Ghost
(Front Row) Immortal, Omni-Man

The first incarnation Guardians of the Globe appeared in Invincible # 7. This version was a parody / homage of the Justice League of America. The members were Darkwing (Batman parody), who is like Batman without the ears; Red Rush (Flash), a super fast Russian; the super strong War Woman (Wonder Woman), who may be a lesbian; Aquarus (Aquaman), who is more fish than man; Green Ghost (Green Lantern), who can phase and fly via a gem he appears to shallow; Martian Man (Maritan Manhunter), who can shapeshift and fly; and Black Samon and the Immortal (the only non-JLA parodies members). However, the dialogue suggests there was another Green Ghost who was a member. They were all sent to their based in Utah only to be killed by Omni-Man (a supporting character of the comic). Only Black Samon (who wasn't on duty at the time) and the Immortal (due to his powers) survived. Robert Kirkman (the writer) explained the reason for the JLA parodies was "I have 18 pages to introduce them and make readers care about them before I killed them. Using archetypes is the best way to that".

The team with their own book

The next team was formed by the US government after the murder of the first. It was supervised by government agent Donald. The team consists of Dupli-Kate, Robot, Rex Splode from Teen Team; Black Samon from the original team; and new characters Monster Girl and Shrinking Ray. The team did poorly, leading to changes: Bulletproof and Immortal joined. Shortly, the Immortal became leader. Most of the team's most powerful members had to stop a martian invasion, while the members on Earth had to stop the Lizard Legion from taking over nukes. Soon, Dulti-Kate and Shrinking Ray died.

A parody ad "advertised" fictionally a Guardians of the Globe mini-series. However, a real series came out. The team started out with Brit, Yeti, Bulletproof, Outrun and Kaboomerang. However, El Chupacabra, Pegasus, Kid Thor, Japandroid, Cast Iron, Le Brusier, Best Tiger and Knockout joined as the series went on.
My sources were Wikipedia's page on the subject and Invincible volume 2 "Eight is Enough".