Are you talking about the font used in the name Shrek itself_?

both.

but more about the fonts used for the actors’ names

Those are not fonts, the letters are made by mud and stuff. I don’t think the character shapes are based on any existing typeface. Duplicate characters look different — no two letters are identical.

thanks

Dunno about the original font used in the name Shrek but here is a similar free font,
http://www.dailyfreefonts.com/fonts/infos/1861-Shrek.html

Rest everything I guess were designed and animated in 3d softwares like Maya or XSI itself.