Blue creepers? Does anyone know why? [closed]

Solution 1:

In the vanilla game, charged creepers have a blue "sparkling" outline. Charged creepers are formed when lightning hits near a normal creeper. This is usually a rare occurence, but you may see more than one during a lightning storm considering creepers spawn in mobs and creepers in a radius of 3 to 4 from a lightning strike are converted.

Other than that, you could just be seeing a graphical glitch or have an (outdated) resource pack override your creepers skin.

Solution 2:

There are blue creepers (dubbed "Mana Creepers") from the Ars Magica 2 mod.

It's definitely blue.