Bare Bones - Boss Bars

This pack gives the vanilla boss bars their own artwork to give more spectacle to fighting bosses.

Raids also feature unique victory and defeat messages.

Using ResPackOpts, you also have the option to make the Wither bar blue, matching other depictions of soul energy in Minecraft.

(3D Tools from Bare Bones - 3D Tools)

Limitations:

Due to just being a resource pack that changes the Wither and Ender Dragon translations, anything else in the game that uses their name will instead show the boss bar sprites. This includes chat messages, and death screens.

There are probably ways to fix this using a mod or core shaders, but I have no plans for this at the moment.