Essential to any new company's success, but may appear mad/dormant/useless to staff members other than the Wise Man, and especially to the Willing Slaves. Once in a while (or maybe only once), comes up with a "crazy big idea" that becomes the basis for the company's value proposition and millions in future exit value (provided the idea is executed by someone other than the Visionary). During productization, the Visionary's input risks being completely forgotten, with possible result of ouster, osterization, and future drinking problem. When teamed with a Wizard and a Wise Man, can become enormously successful. When kicked in the pants enough, can become a Wise Man (rare - drinking problem more likely - but possible).
Visions tend to remain inside the heads of Visionaries (or on the pages of a business plan) in the absense of a Wizard. It is the Wizard's job to not only create a tangible expression of the Visionary's dream, but to preferrably do so using a level of magic that borders on proprietary. Beware the Visionary-Wizard combination: sometimes the Visionary can wake up with an entirely new vision in mind - if that person is also the Wizard, formulas/products that were on the verge of completion may suddenly evaporate.
The Willing Slave
The Willing Slave is what may be called in some mature companies a workaholic. He/she wishes nothing more than to maximize their output during waking hours. A genius-grade, well-managed Willing Slave can create exponentially more value than whole armies of non-willing slaves (contractors), and will willingly work to bring the magic of the Wizard into the light. But the risk of burn-out is great, and if there are more than one Willing Slave in the room, the Wise Man must step in and provide guidance.
The Wise Man
Behind almost every successful start-up lies a Wise Man. Sometimes VCs put them in place as COOs or executing CEOs because they understand that the Visionary may be too busy dreaming up new ideas to execute, the Wizard has too little interest in the ROI, the Closer will sell anything, and the Willing Slave needs to be worked at the correct pace. The Wise Man has been there, done that. He's seen it all before. He knows a year has only 250 workdays and knows exactly what can be accomplished in that time. He knows that delivering too quickly causes quality problems, and deliverying too slowly will kill the company. He knows the time-value of money and is usually a pretty good judge of legal risk issues and spreadsheet jockey. Don't hire the Wise Man at your peril.
Companies die (and/or never get funding) without the Closer. Closers are able to take a product based on the dream of the Visionary, the magic of the Wizard, the guidance of the Wise Man, and the work of the Willing Slave, and sell it with such force that not only does the product get sold, an army of advocates is created - the buyer of the product becomes a Closer of equal capability. This is what VCs call "achieving scale". Good closers can do it by phone (and are seldom seen without one to their ear), better closers know that networking and face to face can greatly expand scale - the best closers understand how to close to millions simultaneously via email or AdWords or a viral video, to anyone, anytime, anywhere.