if you have religions in your world, chances are there are some creatures that are deemed holy, right?
in my world, white stags are considered holy (at least to celestial fairies). the legend is that there are three white stags in the human realm which are the reincarnations of the three queens: meave, mab, and macha. some humans believe the stags have magical properties if they kill them. two of the stags die in the first and second novels, and the heart of the stag in the second novel becomes a really important plot device.
For mine there are two special wolves (one white the other black) both identifiable by there human like eyes (both have blue eyes with round pupils) and they are believed to be good and evil but really (like yin and yang) they have both have good and evil in them, and they are believed to be of infinite power. That mine.
The most interesting "Higher Being" in my universe is A superintelligence made from Ancient Stone-magic computers called Uem. while it nearly had the knowledge and perception of any of the other new gods, called the great lords of new, it was limited by its physical constraints from reality, unlike the great lords. It was built by an extinct species called the Y'lahil, and among them were "Uem monks" who directly connected their knowledge to Uem's. The select few who didn't go completely insane passed this knowledge on to the Y'lahil, helping them build a weapon to dis-throne the gods.
The beasts that are considered most 'holy' in my universe are dragons. They're considered to be creatures that're next to gods and goddesses. Humans were told that the dragons descended from the gods to protect them from harm's way. Generations upon generations, dragons fly off to replace the old in performing duties assigned to them by the gods. Their eggs are left in a sacred temple to be cared for and protected. To kill or smite one is considered a federal offense and a grave sin to the world. Legends say that anyone who spills the blood of a dragon is destined to live a life of misery and despair.
Owls are often considered holy or spiritual in my world.
Albino creatures are considered by some to be 'touched by heaven' and thus, holy.
Other cultures shun them for their stark red coloration, as creatures of blood and death.
In my story the 'holy' animals are the five white cats. They are the guardians of the realm and supposed to keep all who mean it harm out. These cats are huge and include a Tiger, Cheetah, Leopard, Lion and Serval all with their black stripes and spots. The lion's mane is black. And while they are supposed to protect the land if someone has ever entered with good intentions then they will forever pass the test no matter what their intentions change to.