Nciku tells me the proper measure word is 类, but a quick search on Google garnered mostly results like "哪类角色更容易赢“小金人”？“ implying that for the most part 类 is used when inquiring about a particular type of role. Does that mean that 个 is fine in most general statements?
Same as English,角色 is a noun. For example,when there are only one person,we use "is"after words which express that,when there are many,we use "are". "角色" is the same as what I described,when you want to express many "角色"，use"类"，it won't be wrong,when you just want to say one "角色"，use "个"
- "类" is used for describing a type (a class) of 角色.
- "个" is used for referring to a particular 角色.
Yes, you are right on 类. 个 is more general for 角色.
Example: 你扮演哪个角色? you can also ask 哪类... but the two sentences will have different meanings.