Requirements: None except for our beloved game (Fallout 3 GOTY). 
Contents: No plugins. Just three modified skeleton.nif files. 
Installation: This is a replacer. The usual, simple task of copying and pasting should do it. Manual installation or mod manager method... it's your choice. 
Uninstallation: Just delete the skeleton files (skeleton.nif). Or unstall them through a mod manager if you used a mod manager method when installing. 
What does this mod do?: Self-explanatory. Don't expect too much from this mod. This is just a fun mod that I made quickly uisng vanilla skeleton files. It's just an experiment with a small idea that came to my mind. Yesterday I just learned how to modify skeleton files and I wanted to test it. No more no less. 
Possible Issues:
- It's possible this mod can cause some problems in some narrow areas filled with super mutants becaused of their super big heads. It is also possible those issues are not issues at all. What I mean here is that it is possible the main quest progress at a certain point is impossible because Fawkes are also expected to be super big headed. If this happens I will make all super mutants' height shorter than their current height and reducing their head size a little bit too. Anyway if this problem happens, please don't hesitate. Just report the problem to this mod page so I can fix the problem. 
Found Issues: 
1. Mutant's heads are fun to watch but their necks are ugly because head morphing is done by a simple modification to the skeleton files. This ugly neck problem is now almost fixed in ver 1.1. Not fully fixed. Small ugly neck problem still exists for standard types of super mutants such as brutes and masters and etc. I will fix this later. 
2. When you take a head shot in VATS mode, there is a problem that most of the bullets you shoot wasted. Just don't aim head in VATS mode! A kind of useless mod in my opinion. Just a fun mod. If you can fix this problem, please go ahead. Make your own mod or you can try to help me this way. I don't care. Just do it if you can! 
A workaround to the found Issue #2: 
- Since head shots in VATS mode are useless to the big headed super mutants, I recommend you to use DK_BulletTime instead of the VATS mode. I believe we wastelanders all love DK_BulletTime mod. 
- Head shots to the Super-Big-Headed Super Mutants in VATS mode seem to be working now in ver 1.1. 

Note1: My first creature mod for Fallout 3. It's possible I can make more creature mods in near future. Not sure about this though because my free time for modding is quite limited. 
Note2: Inspired by Hulk sized Supermutants mod by c.i.b. (An idea first came to my mind and then I found this mod on Nexusmods. After then another new idea came out. "The big headed super mutants.")
Note3: Super big headed overlords and behemoths files will be uploaded later. Then fomod installer at the final step. All files are uploaded including the fomod installer. No fomod installer. 
Note4: Altough all super mutants are human-like voiced except for behemoths, they are classified as creatures in Fallout 3. 

Assets and Tools used for creating this mod: 
Vanilla super mutant skeleton files by Bethesda, Bethesda Archive Extractor (BAE), Blender 2.49b, NifSkope, and FOMOD Creation Tool. 

Permission: 
Feel free to use this as a mod resource but please don't upload it to other websites unless otherwise stated. 

Credits: 
c.i.b, Bethesda, BAE developers, Blender and its related scripts developers, NifSkope developers, and FOMOD Creation Tool developers.