U-Men

Belief System

The U-Men's belief system around the teaching of the fictional John Sublime. They believe the world is imperfect and must not be exposed to "fallen Earth". As such, they wear special containment suits (although they have to pay for the suit themselves) and only eat special "clean" food.
The true insanity of their religion is that they are humans that harvest the organs of mutants and implant the organs in themselves to get super powers. However, this process can kill them if the organ aren't transplanted right. They believe this turns them into a "Third Species" ("Homo perfectus" as Sublime calls them) and will steal the mutant organs of dead U-Men. They use special weapons (such as bullets and razors) to get said organs.
U-Men work in teams. Each squad has a team leader and his/her lackeys. These team often go on mission to collect organs.
Appearances
We first saw the U-Men as a group of them hunt down Angel Salvadore (who has fly-like powers). They are about to dissect her until Wolverine attacked and get killed. As such, more U-Men attack the X-Men's mansion only for Jean Grey and several students defeat them sending them running away in fear.
Next time we see them, Xorn was taking a class on field trip. Xorn gets distracted and left the group. A single U-Man got beaten by the students. The students discovered Xorn "slain" other attacking U-Men.
Kid Omega and his gang got high on a drug called Kick. Drunk, they decided to attack an U-Men headquarter. They end up killing several U-Men. Why are we suppose to treat them as threat?
A single U-Man was attacked by mutants on Planet X.
References:

• http://en.wikipedia.org/wiki/U-Men_(comics)

The OTHER Iron Man

He is the guy in the metal underwear (in case you were wondering).

Yes, there is a character named Iron Man that isn't owned by Marvel Comics. This Iron Man was created 1941 thus making him the first Canadian superhero and predating Tony Stark. Despite the pitcure shown above, the comic was actually one of the few colored (most Canadian comics at the time were black and white).
Iron Man was a member of a race of an amphibious human mutants that lived in the South Seas. However, an earthquake killed all of them save for Iron Man. He lived in a sunken castle (mourning the rest of his race's deaths) until World War II. He was "summoned" by someone named Major and two kids. He decided to fight the Nazis (who he thought were no better than the pirates he hated ... just roll with it).
He has various super powers. As mentioned before, he is amphibious. However, he is also super strong (allowing to punch through steel and jump higher than normal person) and indestructible.
My source was:

• http://en.wikipedia.org/wiki/Iron_Man_(Canadian_comics)

Danny Chase

Danny Chase was a short-lived member of the Marv Wolfman-era Teen Titans comics. He was intended to be a comic foil to other characters (especially  Beast Boy). However, because he criticized the other member despite being useless in battle, he came off as an egoistical and rude brat. As such, he became extremely unpopular with the fans. Despite Marv's attempts to make Danny more appealing, the negative reception was enough to have Danny written out of the series.
Danny was the son of international spies. As such, he was trained in being a spy himself. For unknown reasons, he had telekinesis and photographic memory. He joined the Teen Titans. He briefly became "Phantasm", using a hockey mask, fabrics and robot-voice simulator (that he stole (Our hero!)) to hide his identity. He gave his life to save Azarath (Raven's home world). His and other souls merged into a being called "Phantasm". This being has appeared time to time in various DC Comics since then. Brother Blood briefly brought Danny back as a zombie. In the Blackest Night event, his body was turned into a Black Lantern. However, Dawn Granger destroyed the Black Lantern Danny.
Danny's main power was telekinesis. However, the power is extremely limited. He could levitate himself when sitting Indian-style and throw small  objects, which annoyed people more than hurt them. Despite claiming to be a super-spy, he would panicked during battle thus enforcing idea he was a useless jerk.
My sources were:

• http://en.wikipedia.org/wiki/Danny_Chase
• http://tvtropes.org/pmwiki/pmwiki.php/CreatorsPet/ComicBooks

The Captain

The Captain is a parody superhero that appears in the Nextwave comic series. He is a fouled-mouth, cynical and hard-drinking  superhero. He wears in civilian clothes like the rest of the team. More specifically he wears sneakers, a trenchcoat, camouflage pants and a t-shirt with a black star.
Little is known about his past. What we do know may not be true since the comic Civil War: Battle Damage Report claims the team might have had their mind and memories altered. He claims to be "from ☠☠☠☠ Brooklyn". He was born while his mother was listening Roxy Music's Avalon. His mother hanged his teddy bear leading him to hate teddy bears even to this day. As an adult, he was drunkenly walking around Brooklyn when two aliens, Spa-Fon and Squa-Tront, gave him with the power of "the Heartstar of the space between the galaxies" to make Brooklyn a better place. However, he mistook them for leprechauns and attacked them.

He became a superhero for unknown reason (claims it was "for the mask" despite him not wearing one in the entire series). He became Captain ☠☠☠☠ ("☠☠☠☠" being a censored cuss word so bad that Captain America beat up and shoved soap in his mouth). Then, he tried the names Captain Kerosene, Captain Marvel, Captain Avalon, Captain Avenger, Captain Ultra, Captain Universe, Captain L. Ron, Captain Ron and Captain Power, but had to give them up since other people already took them before him. He eventually had to pay a "marine-looking melon farmer" for his current name. A text box claims that the Captain is not a captain of anything. According to his fellow Nextwave member Aaron Stack, Captain cannot remember his real name and uses Captain as his name.

He joined Highest Anti-Terrorism Effort (H.A.T.E.)'s superhero group the Nextwave. However, he and the rest of the team went rogue when it turned out H.A.T.E. was working for terrorists known as the Beyond Corporation. He helped the team defeat the Beyond Corporation and H.A.T.E.
The Captain has a "generic set of super-hero abilities". He has super strength, super durability, flight and super vision. He has been shown fight the Godzilla-like Fin Fang Foom and even managed to brake one of Fin's fingers with his bare hands. However, when was trying to get his name, he was seen getting beaten up by multiple people. Alcohol does not hinder his super powers although he can still get drunk.

Resources:

• http://en.wikipedia.org/wiki/Captain_(comics)

Interlac

"As the official U.P. language, Interlac is taught in schools throughout the system and is the common form of communication between most sentient United Planet races."  - Who's Who in the Legion of Super-Heroes #   1

Interlac is a DC Comics fictional language. It is the main language used by 30th century United Planets (think the United Nations IN SPACE) in the Legion of Super Heroes comics. It was first referenced in Adventure Comics # 379.  However, the actual letters and numbers weren't reveal until years in Legion of Super-Heroes (Volume 2) # 312 by writer Paul Levitz and artist Keith Giffen. 
Language / Numbering System
The language has 26 letters that corresponds with each the English letters and it's numbering system uses a ten as a base (as shown above). As such, it has ten digits corresponding with 1, 2, 3, 4, 5, 6, 7, 8, 9 and 0. However, the numbering system is flawed due to 42 and 7 looking the same. It has a similar problem with 41 and 6. Despite being written differently, Interlac sounds exactly like English.
Babylon 5
In Babylon 5, there is an unrelated language also called Interlac. This version of Interlac is a universal language based on math. This is flawed idea to the possibility of aliens having non-decimal based numbering system.
Reference:
http://en.wikipedia.org/wiki/Interlac

Mercury Man

Mercury Man was a Golden Age superhero who has fallen under public domain. So, now anyone can use him without approval from his original publisher.
Merco was an alien from the planet Mercury. They were "ruled by greed, hatred, and fear". Since they have super advanced weapons, they ended up killing each other in nuclear Armageddon. However, Merco managed survived because the radiation gave him super powers and turned him metallic... for some reason. He had small wings on his ankle and had wing-like ears. He went to Earth as the superhero Mercury Man to prevent the Earth from suffering the same fate. He stopped a nuclear attack on the US. Dr. Penn (a female scientist he met) gave him the power to become a normal human and turn back (although his metallic form was the only time he could use his powers). The next time we see him, he (now in a different costume) takes various "warmongers" to Mercury to show what could happen to Earth if they don't change their ways and trap them there when they refuse to do so.
Merucry Man has a variety of powers. He can fly, turn into mercury, fire disintegration bolts, use minor telepathy (which allows him to find people) and has super strength. He has also been shown surviving in the vacuum of space and the explosion of a nuclear bomb. He also has scientist-level intelligence.
My sources were:

• http://pdsh.wikia.com/wiki/Mercury_Man
• http://en.wikipedia.org/wiki/Mercury_Man
• http://www.comicvine.com/mercury-man/29-71497/

Grasshopper

Neil Shelton

The Grasshopper(s) is a series of parody superheroes of the same name that each die shortly after they are introduced to spoof the tendency of superheroes dying and being replaced by a new hero with the same name. My main source was Wikipedia.

Doug Taggert
He was an employee for Roxxon Oil (an fictional oil company). He was a security guard that used a suit of power armor allowing him to jump superhuman heights, but provides little to no protection despite being armor. Doug has a crush on  his co-worker Cindy Shelton, who has a crush on the Grasshopper (his alter ego). He tried to stop a robbery and joined the Great Lake Avengers... for five seconds, since the Batroc's Brigade (the people committing the robbery) killed him shortly after.
Neil Shelton
Neil was another Roxxon security guard that gained Doug's suit. However, it was altered and was more like Iron Man's. Cindy Shelton fell in love with him thinking he was the original Grasshopper. Unfortunately, she was Neil's cousin. So, Neil used his "Maximum Jump" to avoid her, which (according to Doorman) killed him because he exited the Earth's atmosphere and burned upon reentry into the Earth's atmosphere.
Unknown
A person claiming to be "The All-New Grasshopper" was a member of the GLA (now called the "Great Lakes Initiative"). His neck was snapped by a disgruntled Deadpool when the latter was kicked off the team.
Skrull Impostor
A fourth Grasshopper joined the team. He was revealed to be a Skrull (a type of shape shifting alien) impostor. Mr. Immortal (the team leader) was shocked while Big Bertha (a female member of the GLA) thought it was obvious.
References:

• http://en.wikipedia.org/wiki/Grasshopper_(comics)