UVs and shaders

If I just wanted a simple colored shader on my poly character
do I still need to UV map it first ?

if you are just applying a flat uniform color you do not need UV’s

The simplest answer to this is just give it a try!
CG is about making things look good, right? If you give it a try, and it looks good, then it is right.

You asked a very binary question. Either it works, or it doesn’t. If I were asking this question, I would have said something like: “Are there any problems with not UV mapping my character if I only want to put a simple shader on it? I don’t think there are any problems, but I’m not 100% sure.”

Framing it like that shows you’re not just asking because you hit a snag, but you’ve recognized the limits of your own knowledge. I know it’s a subtle difference, but saying (or even better, showing) you’ve given a problem some thought … it matters. You’re asking people, not Google.

That being said, uv are really useful in several fields (fx or comp for instance). Not having any uv might add difficulty, depending on what you want to do down the line.