The Dragon Ball franchise is named after the titular wish-granting objects used to summon the Eternal Dragon, Shenron. Given his role in the story, Shenron would seem to be one of the most powerful entities in the cosmos. That is not the case, and he genuinely has some quite strong worries.
Shenron is plainly terrified of Lord Beerus from Dragon Ball Super, who had an unanticipated effect on him. While this makes it logical, Shenron appears to be unafraid of other powerful entities. After all, he's not immortal, and even many of the weaker Z Fighters should be able to take him down. He is the reason Shenron should be terrified of many other characters, including Goku and Vegeta.
Dragon Ball's Most Important Character Isn't All That Powerful
As mentioned, Shenron isn't a god himself; he's likewise as mortal as many of the other characters seen throughout the franchise. In fact, his mortality seemed to be tied to a statue that Kami restored in order to revive the dragon, this event speaks volumes about how much power he really had. In the penultimate saga of the original Dragon Ball, the evil Namekian King Piccolo actually killed Shenron after the latter granted his wishes.
This rendered the Dragon Balls inert and thus kept anyone from using them -- and Shenron's wishes -- against him. At the time, this feat was a big deal on several levels. For one, it took the series' biggest plot device out of the picture. It also showcased just how powerful King Piccolo was compared to the likes of the Red Ribbon Army and other previous enemies of Goku.
Of course, King Piccolo was not the last villain Goku faced, as his reincarnation/son went on to become a powerful friend of the Saiyan. Because of the series' legendary strength creep, progressively lethal adversaries have to be added, with those fought in the current Dragon Ball Super making King Piccolo look like the hilarious weakling Emperor Pilaf. Not only are these terrible guys extremely powerful, but Goku and his comrades must become equally so in order to defeat them. Given what has been shown thus far, this means that any of them could easily kill Shenron.
Shenron Should Fear Goku Just as Much as Lord Beerus
Shenron has mostly been portrayed in a taciturn manner throughout Dragon Ball, wanting little to do with those begging him to grant their wishes. This usual character was completely broken at the mere mention of Lord Beerus, with the cool, calm, and collected dragon becoming incredibly nervous and flustered. The worry stemmed from Beerus' immense power, as he's able to destroy worlds as if it were nothing. With how fickle Beerus can be, it's no wonder Shenron or anyone else came to be afraid of him. It also makes sense that Shenron knew about him, especially since villains like Frieza had heard of Majin Buu and knew to avoid him. What doesn't make sense, however, is the singular apprehension Shenron has toward Beerus and the fact that he lacks such a reaction to anyone else.
As mentioned, Shenron can be killed; King Piccolo did so with a power level of 260. By the conclusion of Dragon Ball Z, Goku's Super Saiyan 3 form had a power level in the billions, easily eclipsing the foes he had fought in his youth. Thus, killing Shenron would be a piece of cake for him or any of his allies, with even relatively "weak" humans like Krillin being much stronger than King Piccolo by the time of Dragon Ball Super.
It may be claimed that Shenron doesn't fear Goku and the others because of their heroism, but the presence of Goku Black demonstrates that they're just as capable of immense evil. Similarly, Goku has a history of enlisting villains as allies, giving Shenron reason to distrust him. Shenron should be terrified in their presence, especially since Bulma has a Dragon Radar that can rapidly find the Dragon Balls. Lord Beerus isn't the only one he should be terrified of, and escaping Goku and the group could be the answer to Shenron's own wish.
