All that needs to be known is that this mod brings giant creatures to your world with godly stats and powers. They are so powerful that they got members of their own species to worship them. 

When playing the game normally, the titans really only spawn through means of titan spirits. They can be taken down easily with powerful gear. The powerful gear will be unnamed so you may experience this all for yourself.

That being said, you may just want to spawn these titans for yourself. They will engage in titan brawls if they find themselves near each other.

Just be warned you aren't safe in creative mode from them.
 

Below is an image of "Witherzilla".

These titans are waiting for you. 
Once again, huge shoutout to enderman of d00m as the OG maker of the mod, I am only porting it.

Here was the permission:

That being said, there is a video for this addon:
 

So, have a good time.

The titans addon has gotten an update but it is important to recognize that the mediafire link may not be spread. Be sure to link this page.

There is a video for this:
 

v5:
this update brings in newer features from the newest beta for the java edition of this mod. as a bonus, there is now a warden titan in the semi-port.