In Hexxit, the End is generated exactly as in Vanilla with added several Enderman shaped obsidian towers and occasional Battle Towers.
The Enderman Towers
In the End, several obsidian towers are shaped as Enderman. In each tower there are two Ender Crystals which will of course heal the Ender Dragon. They can be shot with a bow and arrow through the eye holes.
Inside the statues there are ladders which lead to the head and tripwire traps which will cause TNT to explode. The TNT is hidden behind gold blocks. Inside the head there are sponge blocks which are stopping lava above them.
There is no loot in the towers apart from 10 gold blocks, quartz blocks and TNT, however the statues are partly underground and at the bottom (under each leg) there are 8 diamond ores. Due to the usage of quartz in weapons for Tinkers' Construct, this can be an extremely good source of quartz. The quartz blocks are designed to look like the internal skeleton of the Enderman towers.
Dungeons
Battle Towers are also sometimes generated in The End.