The animals with the largest penis-to-body ratio are all over the map. with relatively giant penises, and others are hulking mammals with members to match. There's even an animal on here that has a penis 50 times the size of its body.
Elephants and odd hoofed mammals (like rhinos and horses) have The largest penis (belonging to a blue whale) ever measured had 2,4 m.
In the animal kingdom, there are many, many penises. But the biggest penis of all belongs to the largest animal that has ever lived, the blue whale. The average.