Darkseid isn't afraid of many things or people in the DC Comics universe, but the ruler of Apokolips fears a big villain for very good reasons.
While DC supervillain Darkseid isn't terrified of many adversaries, weapons or forces in the galaxy, one villain, the Black Racer, is admitted to have, like others, planted fear in the heart of the Apokolips ruler . In Final Crisis, Darkseid is revealed to be terrified of the deaths of the New Gods versions, as they represent the very real possible end of the mighty villain's reign in the DC Universe and the end of his evil reign.
In the Final Crisis crossover event with Grant Morrison, J.G. Jones and Carlos Pacheco, Darkseid acquires the Anti-Life Equation and unleashes it on the world. However, after nearly defeating the multiverse and bringing the greatest heroes to the brink of defeat, Barry Allen and Wally West's The Flash managed to bring the black car into battle. The New Reaper's origins are tied to the ruler of Apokolips, who confronted Darkseid head-to-head after both of The Flash's heroes surpassed him. The villain can only say, "No. Not you," watching his reign crumble as the Black Racer pursues him, while the heroes heal those infected by the Anti-Life Equation. Along the way, Black Racer is revealed to be the only villain Darkseid Admit that he is genuinely afraid.
The Black Racer Is Tied To Darkseid's Own Origin
Darkseid's fear of the Black Racer is fitting, as the origins of these two new gods are closely tied to their time on Apokolips. The supervillain claims that the Black Racer is his "most powerful weapon" and after he takes control of the planet, he grabs Death and straps it to his host (like the Flash in Darkseid Wars Same). As a result, Black Racer serves his master as the embodiment of death in the DC universe to carry out his evil orders.
Darkseid's existence is essential to his mission to shape reality in his image using the Anti-Life Equation. He is not afraid of pain or injury, but the one thing the villain fears most is his own death. So, with Black Racer's ability to knock him off the board, Darskeid even admits that Black Racer can -- and has -- put an end to his evil plot.
Ultimately, the Black Racer proved to be the perfect weapon against Darkseid, as he ended up killing him in Final Crisis and Darkseid War (the latter being Death possessed by Flash). With the New God villain able to end his Existing, Darkseid, despite being one of the most menacing villains in the DC Universe, is understandably afraid of the Black Racer.