The Squadron Supreme is at the heart of a major event in current Marvel Comics, Heroes Reborn, which imagines a world in which the Avengers never existed. The Squadron Supreme takes their place, but the team has been around for quite a while, first appearing in 1971. The team features a lot of powerful members, including some of the most powerful in Marvel Comics.
The early rosters of the team might feel a little familiar to comic book readers, but that's intentional. The team was deliberately a pastiche of the Justice League Of America, meaning that many of its members feature the same kinds of powers as some of DC Comic's most powerful superheroes.
Nighthawk
There are many alternate versions of Batman, and in some ways, Nighthawk is one of them. Nighthawk is an original member of the Squadron Supreme, created by writer Roy Thomas and artist Sal Buscema in Avengers #85. He consciously takes after Batman in his appearance and lack of powers.
Nighthawk is just an average guy trying to do right, but he does amazing things in his home universe of Earth-712. He eventually becomes President of the United States and even finds himself in opposition to his team as they install themselves as rulers of their world.
Tom Thumb
Thomas Thumb is a genius on par with Tony Stark and Reed Richards, designing the headquarters of the Squadron Supreme and a lot of their most inventive gadgets. But he has no superpowers of his own, making him among the least powerful in the group.
His inventions put him ahead of some others, though, as he designed a special force field generation to protect him from enemy attacks. He also created a behavioral modification machine, which played a key role in the team's attempt to create a utopia in their world.
Blue Eagle
James Dore originally debuted as the American Eagle in 1971, but by the time of the 1985 Squadron Supreme comic book mini-series, he was the Blue Eagle. The Blue Eagle had no powers of his own but wore a special suit that featured synthetic wings that allowed him to fly.
In this way, he wasn't too different from Sam Wilson, the Falcon, though Sam later developed a telepathic link with birds. James Dore was also a highly skilled hand-to-hand fighter and expert with a variety of weapons.
Arcanna
Arcanna may be the most familiar member of the team to fans of the MCU, but just barely. Dottie Jones appeared with her husband Phil in WandaVision, though the two live-action characters didn't exhibit any overt connections to the Squadron Supreme. Arcanna is a powerful witch, but not on the level of Agatha Harkness or other Marvel magicians.
Arcanna steps back from the team after marrying Phil Jones and having a child and is mostly out of the superhero game in the '80s. Later reboots, like Supreme Power, showcase a different version of the character.
Nuke
Nuke is very powerful, able to absorb nuclear radiation, which he can then convert into explosive bursts of energy. Albert Gaines obtained his powers through an accident at the nuclear power plant where he worked. Nuke eventually discovers he emits ambient radiation which gives his parents cancer.
This tragic detail seems to take a cue from Dr. Manhattan from the Watchmen, but this development with Nuke actually predates the iconic 1986 Watchmen mini-series by about a year.
Whizzer
Whizzer might also be familiar to fans of the Scarlet Witch and Quicksilver in Marvel comics. For a long period of time, he was their father. This Stanley Stewart was created as The Flash-analog for the Squadron Supreme and features most of his speed-based powers, making him very powerful.
Also, like The Flash, he has to consume a lot of food to maintain his energy. The comics later retconned Magneto, the Master of Magnetism, as Wanda and Pietro's father, though this was later changed again in more recent comics.
Skymax
Skymax, or the Skrullian Skymaster, is one of the most powerful members of the team. He exhibits all of the same powers as the Super-Skrull, which include shapeshifting and mimicking the powers of others. In his reality of Earth-712, Skymax was the last surviving member of his people, who were destroyed in a war with the Kree.
He is possibly a character who could appear in the upcoming Secret Invasion streaming series, giving his nature as a Skrull and the role of the multiverse in future MCU projects.
Power Princess
Zarda, the original version of Power Princess, is the stand-in for Wonder Woman on the Squadron Supreme. Like Wonder Woman, she is a member of an all-female society living in seclusion on a mystical island. She has most of Diana's powers, including super-strength, stamina, and the ability to fly.
The later version from the rebooted team in Supreme Power has all of those abilities and more. She's also able to drain the life force out of others to sustain her own, making her virtually invulnerable.
Doctor Spectrum
Doctor Spectrum is one of the first four members of the Squadron Supreme, who actually initially appear as villains, the Squadron Sinister. He's based on the Green Lantern from DC Comics, empowered by an alien gem called the Power Prism.
Like Green Lantern, Doctor Spectrum could create constructs of light and energy, though these were from across the visual spectrum. The prism had actually once been a living being, a Skrull, who was transformed into the gem as punishment for an ancient transgression.
Hyperion
Hyperion is the Superman homage in the Squadron Supreme, and correspondingly one of the most powerful beings in Marvel Comics. He has virtually all of Superman's classic attributes, including strength, speed, stamina, and "atomic vision," a version of X-ray vision.
Like Superman, he also has a serious weakness. His version of Kryptonite is called Argonite, which reduces his powers and abilities whenever he is exposed to it. The Earth-712 Hyperion is a descendant of The Eternals, which makes him so powerful.