When You Cry Out In Your Dreams, It Is Darkseid That You See
When Jack Kirby came to DC Comics, darkness followed after him. He arrived ready to build his own mythology, the interlocking Fourth World, a saga of gods locked in an eternal interplanetary war, with Earth caught in the middle.
And Kirby wasted no time introducing the villain of that saga, a gray-skinned god of evil named Darkseid. What Kirby didn't see coming was that he'd created such a great villain that he would grow larger than Kirby's saga and become perhaps the most important villain of the DC Universe.
Darkseid's first appearance was a cameo in Superman's Pal, Jimmy Olsen #134, the second book of Kirby's tenure as writer/artist. Cameo debuts are often disregarded in favor of a character's first full appearance, but in Darkseid's case, that cameo is incredibly important to who he is. Nefarious businessman Morgan Edge has a brief exchange with Darkseid over video, in which Darkseid curtly admonishes Edge for failing to complete a task. The details of Edge's plan don't matter; what matters is that Darkseid is pulling the strings, and no one who doesn't work for him even knows he exists. We don't yet know that he's an alien, and certainly not that he's a god, but we can immediately tell that he's extremely powerful, especially since Edge, a titan of industry, calls him "Sire" and says, "I am your servant."
Kirby even includes a caption at the end of the sequence that basically says, "You've met Darkseid now! Don't forget, because he's going to become extremely important." And that's exactly what happened.
He was never the main villain of Jimmy Olsen, although people who worked for him often were. He was, however, the antagonist of New Gods, Mister Miracle, and the Forever People, the main books that comprised what Kirby called the Fourth World.
Darkseid's powers, especially in those early stories, are as vast as they are undefined. He doesn't engage in combat himself --- though he does occasionally make people disappear with his eyebeams --- but he's always in control of everything that's happening. He has a strange collection of henchmen and agents with different skill sets, from Desaad the torturer, to Glorious Godfrey, the charismatic cult leader, to Granny Goodness, who runs an orphanage that feeds into Darkseid's army.
One of the earliest stories that defined Darkseid was Forever People #4, "Kingdom of the Damned," in which his agents have built an amusement park in which prisoners are tortured. The prisoners can see the happy tourists having fun around them, but the tourists can't see that anything is amiss, except for small children, who can perceive the real horror. Darkseid even walks around the park himself, with parents taking him for a human in a costume while children run and scream in fear.
Darkseid doesn't beat you up and kill you --- or at least that's not his preference. Darkseid breaks your will and makes killing you unnecessary (although he might do it anyway). He's eternally searching for the Anti-Life Equation, which doesn't kill so much as enslave. Life is freedom, in Kirby's view, and Anti-Life is the opposite of that.
Physically, Darkseid has gotten bigger and bulkier over the years, but the threat he poses is spiritual and psychological.
Darkseid's favorite dramatic entrance isn't an entrance at all; it's to already be sitting in your chair, in your home, when you enter, just waiting for the conversation about how futile it is to oppose him. He's so confident in his unstoppability that he can be totally casual about his plans to crush his enemies, even to their faces.
Because Darkseid isn't just some alien villain; he's the evil inside each and every one of us, the "dark side" of humanity.
Even as he's been treated more physically, and beaten more often, in recent years, it's that core Jack Kirby created that makes him one of the greatest villains of all time. He summed himself up pretty well in Forever People #3:
... I am the Revelation! The Tiger-Force at the core of all things! When you cry out in your dreams --- it is Darkseid that you see!