According to Variety, As Shrek 3 nears pre-production, DreamWorks is already plotting another ogre encore. Studio has begun developing Shrek 4, hiring Tim Sullivan to write the script.

While it may seem a bit bullish to plot a fourth installment before the third one opens, the first two films grossed more than $1 billion worldwide and have been the cornerstone of DreamWorks' vaunted CGI animation operation.

Sullivan landed on the DreamWorks radar by working on several feature toon projects for Jeffrey Katzenberg. Sullivan was invited to pitch a take for a fourth Shrek, and the studio sparked to his idea.

Sullivan hire comes after DreamWorks secured scribe David H. Steinberg to write Puss in Boots, a spinoff involving the character voiced by Antonio Banderas in Shrek 2.

DreamWorks is plotting a May 2007 release for Shrek 3, which has Mike Myers, Eddie Murphy, Cameron Diaz and Banderas once again voicing the signature characters.