You know what happens when you take on Lex Luthor? The same thing that's gonna happen to Superman!
~ Lex Luthor
But with him around you're a parody of a man. A duller, a cripple. Next to Superman, even Lex Luthor's greatness is overshadowed!
~ All Star Superman
The fundamental forces are yoked by consciousness. Everything's connected. Everyone. And this how [Superman] sees things all the time. Every day. It's a cruel joke. The mechanistic clockwork of reality hinging on a precious impossible defiance of entropy, on life. And the clockwork doesn't care. It's like - Like it's all just us, in here together. We're all we've got...
~ All Star Superman
Well, console yourself on what you did prevent. Kill me, and several trillion dollars of major research and construction projects grind to a halt, the stock market tanks, several emerging economies in southeast Asia collapse, and fifteen percent of American wealth vanishes overnight. But since it's just an assassination attempt, we're only looking at a temporary plunge in consumer confidence and minor recession resulting in the loss of three million jobs over the next two months.
~ Lex Luthor to Superman
Why don't you put the whole WORLD in a BOTTLE, Superman?
Alexander Joseph "Lex" Luthor is an admirably self-made man who is CEO of LexCorp, a sizable conglomerate based in Metropolis, as well as the third richest man of the world. However, though he participates in charity events, Luthor is motivated by ego and pride rather than morality. In fact, LexCorp is a front for organized black market arms trades and other shady deals. It was this lust for power that eventually made him the sworn enemy of Superman, who Luthor gradually grew jealous of to the point of attempting to get rid the alien with malicious intent. To that end, Luthor hires and has even played a part in creating some of Superman's enemies, and if he has to battle the Man of Tomorrow or his allies, he will utilize his own war suit.
Death Battle Info (Official)
Full name: Alexander Joseph Luthor
Height: 6'2"/188 cm
Weight: 210 lbs/95 kg
Reason for baldness: classified
Former president of the United States
Once acted as his own son via brain transplant to a new body
Should only be possible for a 12th-level intellect
Death Battle Info (Fanon)
Full Name: Alexander Joseph Luthor
Height: 6'2 (6'11" in armor, over 9ft in Giant Suit)
Weight: 210 lbs (595 lbs in armor)
Despite being a normal human, Lex Luthor possesses a keen genius-Level intellect as well as a photographic memory. At his peak, his vast intelligence and technological know-how is matched only by the likes of Batman. While having some skill in judo, taekwondo, boxing, swordplay, and gun handling, Luthor is the type who prepared for a fight where he has an unfair advantage over his opponent. While he initially carried a fragment of kryptonite on his person while dealing with Superman, or something else to keep the man of steel occupied, Luthor later liquefied it and mixed it with a sample of Bane's Venom into a steroid he injects himself with. While it gives Luthor peak human strength and slightly weaken Superman in his presence, the liquid kryptonite had unexpected side effects. While Luthor now has a heightened superhuman immune system, it also causes him to suffer brief lapses of sanity and long-term cancerous effects on his system. But later reverse-engineering Brainiac's nanites for his use allowed Luthor to remove cancerous cells from his system while enhancing himself further physically and mentally.
During his conflict with Superman, Luthor acquired Kryptonian battle armor and had his top engineers reverse-engineer a suit of power-armor capable of defeating Superman. The first model was powered by a solar battery, but Luthor later made a series of upgrades by combining the technologies of Apokolips and Brainaic into the suit's design. The user gains superhuman strength and durability with the suit able to fire blasts of energy and generate a protective force field around the entire body that enables travel in space.
While fighting a Kryptonian like Superman, Luthor utilizes the kryptonite embedded on his right gauntlet to project a blast of energy, produce an energy blade or energy spikes. The effects vary on the kryptonite used: regular Kryptonite can weaken a Kryptonian to the point that prolonged exposure could kill them, Red Kryptonite can have a temporary and random effect on a Kryptonian like affecting their ability to absorb sunlight, Blue Kryptonite mainly effects Bizarro the same way Kryptonite does to a Kryptonian, and Black Kryptonite can cause the dark aspects of a Kryptonian to manifest as a separate being who can be a wildcard ally.
Lex designed the suit primarily to have as much armor and energy shields as possible to outlast Superman. Lex's suit (including the 'Giant Suit' variation) clearly doesn't have the same level of strength or speed as Superman; but this is irrelevant as the kryptonite itself becomes an equalizer. However Superman (in his later depictions at least) has so much experience being exposed to kryptonite that he gained a slight resistance to it, and so is still able to fight the Warsuit on equal footing.
The Warsuit comes in two different sizes; the basic Warsuit and the Giant Suit (which is basically a much larger and more powerful variation). The Warsuit is about the same size as Lex himself while the Giant Suit is almost as big as Ironman's Hulk Buster and is slightly taller than Doomsday. Lex also has giant mechs with similar kryptonite weapons. In the Legoverse he has other variations of his Warsuit; the Decoy Suit allows Lex to summon Lexcorp robots, the Stealth Suit makes him invisible and the Shield Suit gives him extra defenses.
After Superman was apparently killed, a seemingly repentant Lex decides to take over for the Man of Steel. He creates a more steam-lined version of his Warsuit and designed it after Superman's uniform.
One of the smartest minds in the DC universe
During Crisis on Infinite Earths, Brainiac deduced that only Lex Luthor had the intelligence to determine how to stop the destruction of the multiverse.
Has challenged and sometimes outsmarted Brainiac multiple times.
Is considered on par with the intelligence of Superman, Batman and Gorilla Grodd.
Made many of Superman's enemies, intentionally or not.
Founding leader of the Legion of Doom.
Defeated Gorilla Grodd's attempted coup d'etat.
In terms of his overall fight record, Luthor was able to hold his own against Green Arrow (without his armor), fought Batman and Nightwing single-handedly (with piece of his suit), defeated Supergirl and once incapacitated Brainiac.
Became president, though he was impeached within a few months for his conduct during a doomsday scenario he failed to stop.
Before his predicency, Luthor claimed to have political and economic dominance over all of Metropolis.
Saved Superman's life occasionally, though he's technically his nemesis
Killed his superpowered Earth-3 counterpart Mazahs, which got him a clean slate and honorary Justice League status.
Briefly became a God of Apokolips when he helps the Justice League defeat the Anti-Monitor, later renouncing the power out of bordom.
Opted to honor the late New 52 Superman by becoming Metropolis' new protector
Luthor briefly gained kryptonian powers by creating a chemical cocktail (which Superman later destroyed).
Gained unlimited power by merging with the Zone-Child (only for Superman to 'punch the god' out of him).
Made several gadgets designed to counter or defend against certain superhumans.
Made a device that could reflect Grodd's mind control waves, making Grodd the enslaved puppet.
(In the DC Online alternate future) Lex leads the Legion of Doom to defeat the Justice League; with Lex himself killing Wonderwoman and Superman. 
Discovered the secret identity of Batman.
Injustice Lex Luthor discovered the entire Justice League's identities.
Became one of the most dangerous Orange Lanturns ever.
Red Son Lex Luthor became the US president, won a war against Superman by convincing Superman to enter a self-exile, took over the Earth and led the Earth into a golden age.
Lex's decedents would later colonize krypton; becoming the kryptonian race. (Yes, that means Lex is Superman's ancestor)
Luthor's strongest flaws are his arrogance, superiority complex, rage, and obsession with Superman
Luthor frequently ignores or lashes out against Superman even when Superman is attempting to assist him or save Lex's life.
Suit has yet to equal or defeat Superman, even when using kryptonite
Warsuit's armor and barriers are not indestructible (as Superman is either weakened by kryptonite or holds back his otherwise unlimited strength to not accidentally kill Lex.) Sometimes Superman has destroyed the armor with very little effort .
Lex has been unable to deduce the secret identities of many of his enemies.
Was in initial denial over learning Superman's identity, as he thought Superman would never choose such a humble alter ego (even after making a supercomputer that confirmed his identity). 
(In most stories) Has never concluded that Batman and Bruce Wayne are the same person despite Bruce and Lex interacting with each other frequently for business reasons.
After switching minds with Barry Allen, Lex had no idea who Flash's identity was. 
Kryptonite weapons not as effective against non-Kryptonians
Lex suffers from longterm kryptonite poisoning, which gave him blood poisoning and cancer. (Lex thought kryptonite has absolutely no effects on humans, but this is only the case in short periods of exposure. Lex carried kryptonite around him 24/7 to defend himself against Kryptonians, unaware of the damage to himself.)
Has a bit of a Glass jaw, having been once knock out by Lois Lane slapping him in the face hard.
Has a massive loosing streak against Superman.
Despite his intelligence, he has been outsmarted frequently by his enemies.
Prefers to outsmart his enemies rather than duel them; and thus has very little combat experience with his Warsuit.
Lex Luthor, the God of Apokolips.
Lex Luthor in Mortal Kombat vs DC Universe
Lex Luthor played by Jesse Eisenberg in DC Extended Universe series