Why Jon Stewart and Ralph Lauren Are "Superbosses"

What makes a good boss?

It's a question Sandy Finkelstein, a professor at Dartmouth's Tuck School of Business, tackles in his latest book, "Superbosses: How Exceptional Leaders Nurture Talent to Achieve Market Domination." After 10 years studying individuals who are unusually good at helping others build careers, Finkelstein made an interesting discovery: The most prominent people in many industries mentored a disproportionate share of talent in their field.

He describes these individuals as "superbosses" — people who "are exceptionally adept at developing talent because they share particular character traits and adopt a set of common practices that, taken together, are both rare and extraordinarily effective."

Here, a look at five celebrity superbosses who push protégés to their limits:

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Finkelstein cites the former host of "The Daily Show" as the epitome of a superboss. Not only did the TV personality push talent to meet incredibly high standards on tight, nightly deadlines, but he helped them build their own careers as humorists. Notable comedians like Steve Carell, Stephen Colbert and John Oliver owe much of their success to Stewart's investment in their careers. And recently, when rumors spread of Stewart being sexist, Daily Show staffers jumped to his side, countering that he is "generous, humble, genuine, compassionate, fair, supportive, exacting, stubborn, goofy, hands-on, driven, occasionally infuriating, ethical, down-to-earth."

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Thomas Keller, the famed chef behind The French Laundry in Napa and Per Se in New York, draws salivating patrons from all over the world. But the culinary master also attracts legions of aspiring cooks to his kitchen, where he invests time in their personal growth. "We're preparing them for their future, and their future, honestly, is not with us. There's a wide world out there. ... If it's only about our restaurant, then we're short-sighted," Keller tells the Napa Valley Register. Some of his charges include Rene Redzepi, who runs the restaurant ranked No. 1 in the world (Copenhagen's Noma), and Grant Achatz, who launched Chicago hotspots Next and Aviary.

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Fashion icon Ralph Lauren — the one who built a billion-dollar industry around Gatsby-esque attire that captures the ethos of the American Dream — developed a range of protégés who are industry leaders today. Designers Vera Wang, John Varvatos , Todd Snyder and Tim Coppens all worked for different branches of Ralph Lauren Corp. early in their careers and benefited from the entrepreneur's mentorship. Today, they all have their own fashion labels.

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Pro golfer Phil Mickelson, who's won 42 events on the PGA tour in his 23-year career, is known for ruffling feathers among young players. But it's all in good faith. He regularly plays with and offers advice to young guns Jordan Spieth, Rickie Fowler and Justin Thomas. "He's a great mentor who likes to see the game grow, and so he grabs guys who are still trying to find their feet and forms relationships. It's not like he's giving us stuff to write in a journal. He's giving us crap and trying to be competitive," Spieth tells USA Today.

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One of the most frequently recorded trumpet players and Grammy Lifetime Achievement award-winner Clark Terry, who passed away this year, mentored generations of musicians during his 60-plus year career. Among his students: Miles Davis, Quincy Jones and Dianne Reeves. A huge proponent of jazz education, Terry taught in classrooms, camps and clinics. The recently released documentary "Keep on Keepin' On" chronicles his role as a 93-year-old mentor to blind jazz pianist Justin Kauflin, 23 years old. Musician and composer Wynton Marsalis wrote about Terry's inspirational role: "His spectacular playing made me want to practice (of course) but his warmth and optimism made me want to be a part of the world of jazz."