Mob Outlines
A texture pack that puts outlines on mobs to make them easier to spot.
Mob Outlines
_Mob Outlines_ is a texture pack that adds outlines to mobs to make them more visible. In the Overworld mobs have red outlines, but in the Nether mobs have white outlines.
In this image there's a creeper hidden in the sugar cane. Can you spot it?

Now this is the same image, but with the texture pack.

In this image there's a skeleton. Can you spot it?

Again this is the same image but with the texture pack.

This is a fortress in the Nether and it has wither skeletons.

The image but with the texture pack. Now the wither skeletons are much easier to see.

This is an image in the Nether with the texture pack.

But why don't I just use %%MD0%%? The %%MD0%% function shows the hitboxes of ALL entities. This includes chests, boats, items and others. Because of this, the %%MD0%% function can get very messy when there are a lot of items on the ground. It also shows mobs that aren't hard to see. show hitboxes is a lot more aesthetically pleasing option and also has thicker lines than %%MD0%%.
As you can see, _Mob Outlines_ makes spotting mobs far easier and can even save your life or prevent a big mess. Keep in mind that mobs that are impossible to not see, like parrots or sheep don't have outlines.