Possible candidates - they may be disqualified depending on whether you think their intelligence is a "non-issue" or they are, in fact, intelligent but just don't behave as such.
1. Charlie Gordon from Flowers for Algernon.
2. Jack Shaftoe from Neal Stephenson's Baroque Cycle.
3. Graham Smith from Resonance (http://www.baenebooks.com/p-344-resonance.aspx) by Chris Dolley.
4. Forrest Gump from the same-titled novel. I haven't read the book so not sure if it falls under "comedy" category.
5. John Coffey from The Green Mile by Stephen King.
no subject
1. Charlie Gordon from Flowers for Algernon.
2. Jack Shaftoe from Neal Stephenson's Baroque Cycle.
3. Graham Smith from Resonance (http://www.baenebooks.com/p-344-resonance.aspx) by Chris Dolley.
4. Forrest Gump from the same-titled novel. I haven't read the book so not sure if it falls under "comedy" category.
5. John Coffey from The Green Mile by Stephen King.