Operations engineer

The operations engineer, or "ops person," is responsible for taking a verified build from the quality engineer and deploying it to a production system.

Product manager

The product manager is responsible for articulating the feature set for the product. In some projects the product manager sets the schedule, in consultation with developers and operations folks. (Also called "product owner" in some organizations.)

Quality engineer

The quality engineer is responsible for insuring that the product does what the developer(s) and product manager(s) say it should do.

Software developer

The developer is responsible for writing the code to implement the features the product manager wants.

Support engineer

The support engineer is responsible for responding to questions when the users of the product experience difficulty or confusion.

Technical writer

The technical writer is responsible for writing down what the product is supposed to do, according to the product manager, and what the product actually does, according to the developers and quality engineers. This is tremendously helpful when ambiguity or misunderstanding occurs.