The Omni King Zeno is practically an unknown but has more than a few competitors in the comic book multiverse.
Seeing as Zeno is a complete unknown, we only have Dragon Ball Super to go on. This is only going to be an estimation. Regardless, from Darkseid to the One Above All, more than a few can compete with Zeno.
Here are 10 gods from the comic book multiverse that can compete with Zeno.
Note: Abridged histories, powers, and planetary impacts have been taken into account. Spoilers abound, and these are only the author's opinions.
10 comic book gods that can compete with Dragon Ball Super's Zeno
1) Darkseid (DC)
To paraphrase Darkseid, "Darkseid is." Darkseid is one of Superman's biggest and most persistent threats out there. His appearance that the audience is familiar with is an avatar for his true form, which combines all his previous forms. He's the God of Tyranny in the DC universe and never hesitates to brutalize or put anyone down on his hellish planet of Apokolips.
He's survived planetary destruction, tanked most of the Justice League's mightiest blows, and even outfought entire armies. For the record, he's found gods like Zeus and his counterpart, the High Father of New Genesis for 7 days straight while barely being winded. His signature Omega Beams have destroyed planets and are more than enough to slaughter entire armies by himself.
If he ever gets a hold of the anti-life equation he so desperately seeks, all life and reality will be his plaything, much like how Dragon Ball Super's Zeno tosses planets around. In his true form, he was also capable of slaying other fellow gods with near ease.
The embodiment of the Marvel universe itself, Eternity is admittedly difficult to talk about. Put simply, Eternity is the universe, multiverse, and everything betwixt and between the cosmos. Even according to powerful beings like Dormammu, Eternity is the strongest being in the Marvel universe.
He is able to toss planets around, wipe beings out instantly, and the universe trembles any time Eternity awakens. Every universe in the Marvel multiverse has an Eternity representing it.
3) The Endless
The Endless from DC's Sandman series is another oddity. They are a somewhat dysfunctional "family" of cosmic entities that represent different things: Dream, Death, Destiny, Destruction, Desire, Despair, and Delirium. As their names imply, they have all the abilities and powers associated with their concepts. These are literally cosmic concepts that take different human forms.
There's no real easy way to say they have omnipotent powers that rival even godly beings like Dormmamu and Zeus. They'd certainly give Zeno nightmares.
4) Doctor Manhattan
Dr. Manhattan of DC's Watchmen is more akin to Dragon Ball Super's Beerus when the comic itself starts. By the time it ends? He can perceive time as non-linear, time travel at will, pull others through, erase and create new timelines, walk on the sun unharmed, alter reality, the list goes on.
Zeno and Dr. Manhattan would arguably have a spirited debate about things, or at least, he'd be fun to be around. He's also telepathic and can teleport and requires neither food, sleep, nor oxygen to survive.
A relatively new addition to DC's cosmic lineup, Perpetua is the first creator of the multiverse and mother of the Monitor, Anti-Monitor, and World Forger. Her influence resulted in the Crisis on Infinite Earths as well as all other Crises in DCs history. Her hand literally sparked The Big Bang, and she was able to fight a cosmically empowered Batman who Laughs to a standstill (only losing due to him draining her during the fight).
When she wants things to happen, like someone erased or a galaxy gone, all she has to do is wave her hand or even a finger. Things live and die by her will, even as Darkseid, the New Gods, and even the Monitors found out. She caused the universe to shake when she was released after billions of years of sleep. Even the Gods of Destruction, or Angels, or even Zeno in Dragon Ball Super would do well to beware.
6) The One Above All
The One Above All is goodness incarnate. Though rarely seen in the Marvel universe, they helped to recreate the universe to make sure Adam Warlock was the new Living Tribunal. Despite this, they are able to destroy and manifest themselves as the One Below All to destroy life in the multiverse to create things anew.
Ominipotent, Omnipresent, and Omniscient, he is more powerful than Thanos and is The Presence's opposite. He can create and even revive people, as he did with Beta Ray Bill.
Angels in Dragon Ball Super would probably think of him too much as the One Below All. He's responsible for entities called Qlippoth, demonic monsters, can make Mephisto or Dormammu look small, and has basically made sure Bruce and Brian Banner's lives were absolute hell thanks to being the source of the gamma radiation that gave birth to The Hulk. No doubt Zeno will be alerted to his presence and hopefully stay on the One Above All's good side.
7) The Spectre
DC's Wrath of God, Spectre, has gone from hosts like James Corrigan to Hal Jordan. He has wielded powers of invulnerability, possession, and reality alteration through them and can make himself giant. He's stood against Superman, Shazam, and other magic users in the DC universe. In the Day of Vengeance storyline, he wiped out magic users, Atlantis, and even the Lords of Order and Chaos.
But with such a devastating act? He alerted the Presence and was eventually stopped via being tethered to a murdered detective named Crispus Allen. His almighty powers were lessened as a result. Nonetheless, the Spectre remains in wait to unleash holy punishment. Zeno would no doubt consider the Spectre mean, though fair, as a harsh parent.
Eclipso is the one who set the Spectre on the path of vengeance. Eclipso was the original spirit of God's vengeance, and as that spirit, he had near-limitless power granted to him by The Presence. The trouble is, he started wanting to use it for evil purposes and was stripped of his rank and powers. He maintains a lot to be a serious threat, however.
He's responsible for more than that, as he's mentally manipulated even powerful superheroes like The Flash into his thrall. While he isn't as powerful as the Spectre, it does usually take a lot of magical interference like Doctor Fate or the Phantom Stranger to seal him away.
His only goal is to gain his divine power again and wreak havoc on everyone. Zeno had better get this one and his black diamonds destroyed right away, or else they'll be in trouble. Fortunately, Whis should be able to detect such evil and dispatch people to eliminate it without fuss.
9) The Anti-Monitor
The original Crisis on Infinite Earths villain was awoken at the dawn of time. His powers were so great that he destroyed and absorbed countless universes. Even Spectre was unable to defeat him after being augmented by many powerful sorcerers. Supergirl had to sacrifice herself to give the heroes a chance at defeating him.
It took going to the dawn of time and the combined powers of Alexander Luthor, Superboy Prime, a new Dr. Light, and all the heroes and villains working together (even Darkseid was forced to intervene) to finally see him defeated.
Even then, however, he'd be revived twice: once during the Sinestro Corps war, where it takes the combined efforts of the Green and Yellow Lantern Corps and Superman-Prime to stop him, and again during the zombie event Blackest Night, where he's used as the Black Lantern's power battery.
In summary, the Anti-Monitor would be more than a match for Zeno. Zeno may need the Angels' help and the Gods of Destruction to face this lethal foe, if not super strong warriors from the multiverse like Ultra Instinct Goku and Ultra Ego Vegeta and throw in Granolah and Golden Frieza while we're at it.
10) The Presence
The Presence is God in DC, similar to the One Above All, who goes by many names: the Source, the Hand, and other deities' names. He is responsible for the creation of the DC universe and many cosmic entities like Spectre and Eclipso. He gave birth to all the multiverse and Heaven and Hell. He is ultimately good and opposes chaos and darkness in all its forms.
It's believed that Zeno and The Presence would get along mostly well enough. The universes being destroyed wouldn't exaclty be in Presence's favor, but as long as everything is restored, tensions should be low.