How can I summon a mob with an always-visible name tag?

In Minecraft 1.8, the CustomNameVisible tag only works on Armor Stand entities.

Here is a workaround for putting a tag on a mob. Actually it isn't really on the mob itself, but on an Armor Stand riding it.

/summon ArmorStand ~ ~1 ~ {CustomName:"YourNameHere",CustomNameVisible:1,Small:1,Invisible:1,Invulnerable:1,Riding:{id:"EntityNameHere"}}

You just have to replace YourNameHere by the tag you want to appear and EntityNameHere by the entity name (e.g. Zombie or Skeleton).

It seems like it may be a bug in Minecraft 1.8.8, or maybe a removed feature. There is a way to overcome it though. It may be hard to do, but if it is really a required feature this is the only way I can think of doing it.

Create a clock (click here for a tutorial on how to make a fast clock). Add a command block to the clock with the following command:

/tp @e[type=ArmorStand,name=NAMEHERE] @e[type=!ArmorStand,name=NAMEHERE]

Then run the following command once:

/summon ArmorStand ~ ~ ~ {Invisible:1,Invulnerable:1,CustomName:NAMEHERE,CustomNameVisible:1}

Just replace NAMEHERE with the name you want, in your case replace NAMEHERE with Zorp.

This works because the ArmorStand entity will always have it's name visible above it if it has the CustomNameVisible:1 tag. It is supposed to work on other entities too, but for some reason it doesn't, which I don't know why.