Rational Rose

This begain it's life as a good old fashioned CASE tool, it was to my knowledge one of the first tools to support the UML.

JohnV: Opinion! - This tool shows it's age a bit, but I always considered it to be the "Gold-standard" by which all other UML Tools are judged. It's comprehensive but has it's quirks. It's scripting language is a wacked up sorta visual basic, yuck! It's expensive and given Rationals new RationalXDE and thier purchase by IBM, I would not be surprised to see it get end-of-life'd soon.