Thanos once tried to assemble the worst of the worst in order to regain his reputation as one of the galaxy's most evil villains, and among those considered for one of the spots on his team was Darkseid. The iconic Marvel villain had the top DC Comics villain on the mind because when he was selecting candidates, Darkseid appeared in a small, but excellent secret cameo.
Thanos and Darkseid are the biggest bad guys of their respective comic universes, with both trying to shape the cosmos into their own image through different means. Marvel's Thanos used the Infinity Gauntlet in an effort to impress the living embodiment of Death, while trying to restore balance in the universe. Meanwhile, DC's Darkseid's quest is to acquire the Anti-Life Equation, a formula that allows him control of basically all of existence. Both villains have successfully conquered their respective universes before and achieved their goals. But, when Thanos once tried to prove how evil he was to the rest of the galaxy, he tried to recruit some top villains... including Darkseid.
In the Secret Defenders #12 by Ron Marz, Tom Grindberg, Don Hudson, John Costanza, and John Kalisz, Thanos put together an unlikely team of villains in order to acquire a repository of The Oracle, one of the oldest beings in existence who has been storing "antiques undreamed of," and is celebrated as a God on the planet H'aarg. Thanos says he can't complete the mission because he's been connected to "too many altruistic works acts recently." In an effort to avoid a "holy war," Thanos brings a group of villains plucked from across the cosmos... and when his recruits are shown on multiple screens, Darkseid is among them (seen top right).
Ultimately, Darkseid doesn't make the team. Instead, it consists of Rhino, Geatar, Super-Skrull, Titanium Man, and Nitro, whom the Mad Titan promises riches for completing his task. Thanos specifically chose them because he felt like he could control them - and he's proven correct, as the team successfully completes their mission. Naturally, Thanos gets The Oracle and leaves them to die. It's safe to assume had Darkseid accepted the mission, things would have gotten much uglier.
Clearly, including Darkseid is just an easter egg that references DC's most powerful villain. Darkseid appearing on a computer screen is also reminiscent of his first-ever comic appearance. Although, it's tantalizing to think that Thanos once searched the entire galaxy for a team of supervillains and came across Darkseid. The ruler of Apokolips obviously would never play second fiddle to the Mad Titan, as there's little chance Thanos would ever be able to convince him to do his bidding. Still, it's fun to see Darkseid pop up in a Marvel book, even in a small way.