10.Marissa Mayer

Marissa Mayer

CEO, Yahoo
--Cultural impact
--Most Powerful Women
--40 Under 40

She bought Tumblr for $1.1 billion and revamped Yahoo Mail and the company's Flickr photo-sharing site. And though Mayer's overhauls (from products to workplace policies) stir controversy, she has lifted Yahoo's (YHOO, Fortune 500) user base to 800 million while the stock price has almost doubled this year. Those accomplishments help explain why Mayer, 38, has achieved an unprecedented trifecta: the only executive ever to earn a spot on the Businessperson of the Year list, Fortune's Most Powerful Women list (at No. 8), and Fortune's 40 Under 40 rankings (No. 1).
--P.S.

9.Warren Buffett

Warren Buffett

Chairman and CEO, Berkshire Hathaway
--Cultural impact
--Returnee

He began the year devouring H.J. Heinz, the world's largest ketchup maker, for $23 billion, in partnership with Brazil-based 3G Capital. Now Buffett sits on more than $40 billion in cash, thanks in part to his gutsy investments in companies like Goldman Sachs (GS, Fortune 500) and Bank of America (BAC, Fortune 500) when others panicked during the 2008 financial crisis. As Buffett's pile of cash grows, it's ever more likely that Berkshire (BERK) will make another big acquisition. The Oracle of Omaha hit another milestone this year. In May he joined Twitter and already has over 700,000 followers.
--Patricia Sellers

8.Larry Page

Larry Page

8

Co-founder and CEO, Google
--Cultural impact
--Returnee

Page's seemingly paradoxical formula to re-energize Google (GOOG, Fortune 500) -- more focus and more moon shots -- is paying off handsomely. Shares this year passed the $1,000 mark, pushing Google's value ahead of Microsoft's and behind only Apple's and Exxon's (XOM, Fortune 500) among U.S. companies. As if making sure Google stays No. 1 in search, ads, mobile, online video, maps, browsers, and more was not enough, Page has launched Google's latest zany venture: an anti-aging startup named Calico.
--Miguel Helft

7.Akio Toyoda

Akio Toyoda

CEO, Toyota
--Turnaround story

The Toyoda scion says he follows two rules: "Make ever better cars. And if it doesn't offer fun, then it is not a car." He's succeeding on both counts. Just a few years after the company suffered an embarrassing recall that left a trail of lawsuits (plus the aftermath of a devastating tsunami), Toyota (TM) is back. Toyoda is steering his family's company toward record-high sales of 10 million cars and trucks, as well as record high operating profits, keeping it No. 1 in the world. At the same time he's injecting much-needed flair into its vehicles' design and engineering.
--Alex Taylor III

6.Jeff Bezos

Jeff Bezos

Founder and CEO, Amazon
--Cultural impact
--Returnee

Bezos defied expectations again this year, sacrificing company profits nearly two decades after founding Amazon (AMZN, Fortune 500) to chase (and potentially corner) new markets. The Seattle-based company plowed ahead with its same-day grocery-delivery efforts and partnered with the ailing U.S. Postal Service to allow Sunday delivery in some U.S. cities. Bezos's boldest move? Buying the Washington Post for $250 million with his personal venture fund. Still, his eclectic strategy has paid off in the past, and Wall Street remains as bullish as ever on the stock, up some 40% year to date.
--JP Mangalindan

5.Reed Hastings/Jeff Bewkes (tie)

Reed Hastings/Jeff Bewkes (tie)

CEOs of Netflix and Time Warner

--Returnees
--No. 3 stock price gainer (Netflix)
It has been three years since Fortune named Reed Hastings businessperson of the year; shortly afterward, Jeff Bewkes, CEO of Time Warner (TWX, Fortune 500), compared Netflix (NFLX) to the "Albanian army" -- unlikely to take over the world. There's little dispute now that the business Hastings leads is ready for battle. Its programs are Emmy winners (House of Cards) and buzz generators (Orange Is the New Black), its stock price has soared (up 100% since late 2010), and for the first time it has more paying subscribers than HBO. But Netflix's encroachment doesn't seem to be cramping Bewkes's style these days: Time Warner stock has more than doubled in three years, and it is up 40% for the year, buoyed in part by the media giant's decision to spin off its Time Inc. publishing unit (Fortune's parent). Once he sheds Time Inc., Bewkes will be left with a more focused movie and television business, one that includes HBO. (He already hived off cable networks and AOL (AOL).) If Netflix is the Albanian army, Bewkes's Time Warner might well be the U.K. -- no longer a sprawling empire, but a prosperous place with a clearer sense of identity and purpose.
--A.L.

4.Angela Ahrendts

Angela Ahrendts

CEO, Burberry
--Most Powerful Women
--Returnee
Ahrendts was already having a banner year as the CEO of British fashion house Burberry. The stock was up 29%, vs. the FTSE 100's 10%, despite fears of a slowdown in greater China and continued ennui in Europe -- when she shocked the luxury and tech worlds with news that she was decamping to Cupertino, Calif., to head up Apple's retail and online stores. Ahrendts takes the reins in 2014, and she will oversee an operation with some $20 billion in annual sales (compared with Burberry's $3.2 billion). Analysts expect that she will play a role in helping define Apple's future, especially as technology companies move into new areas, such as "wearables" like Internet-connected watches, eyewear, and other gadgets that are in desperate need of a style makeover. (Ahrendts is credited with helping bring a more youthful image to the 157-year-old trench-coat maker.) Ahrendts's new role makes her the top woman exec at the house that Jobs built, and her success, while critical to Apple's future, will be no easy feat. The last executive to head up the tech giant's retail operations was out after less than a year. If she pulls it off, Ahrendts could be a strong contender for the top job.
--Beth Kowitt

3.'Pony' Ma Huateng

'Pony' Ma Huateng

Co-founder and CEO, Tencent

Ma's Internet empire, Tencent, this year became China's most valuable non-state-owned company, with a market value of more than $95 billion, thanks to a 61% surge in the stock price since January. (Shares are up nearly 10,000% -- no, that's not a typo -- since its 2004 IPO.) Company co-founder Ma, in turn, became one of China's richest tech entrepreneurs (estimated net worth: $10 billion, behind No. 24 Robin Li of Baidu) but arguably the most powerful. He first conquered the Chinese market with his QQ chat service. Now he's setting his sights on expansion around the world: Tencent was reportedly vying for a stake in the popular U.S. app Snapchat in November. Last year it inked a deal with Activision Blizzard (ATVI) that makes Tencent the U.S. gamemaker's exclusive launch partner of a Chinese version of videogame Call of Duty. Ma has his sights set beyond China -- and technology. This year he began heavily promoting Tencent's WeChat messaging app in international markets, and in November, Ma joined another Chinese Internet billionaire, Alibaba founder Jack Ma, to announce the first online insurance business in China. Analysts responded: "Huh? Insurance?" But it seems this tech star is already charting his next move.
--Scott Cendrowski

2.The Activist Investor

The Activist Investor

Clockwise from top left: Carl Icahn, Jeffrey Ubben, David Einhorn, Daniel Loeb

The world's corporate leaders got a blunt warning this year: No company is too big or valuable to escape the threat of increasingly aggressive activist investors. Carl Icahn and David Einhorn bought into Apple, the world's most valuable company (market cap: $467 billion), and loudly demanded that it return more cash to shareholders; Apple (AAPL, Fortune 500) expanded its stock buybacks not long afterward, and now Icahn wants even more. Jeffrey Ubben invested in Microsoft (MSFT, Fortune 500) more quietly, but one can't help noticing that four months later, the tech giant put him on its board of directors and CEO Steve Ballmer announced he was stepping down earlier than planned. Other activists are pushing for change at J.P. Morgan Chase (JPM, Fortune 500), PepsiCo (PEP, Fortune 500), UBS (UBS) -- no company is immune. Activists' new strength isn't mysterious. Major institutional investors are sending dollars to activists, having noticed that activist funds overall have been outperforming the market averages. That's a big reason activist funds' assets have mushroomed from $12 billion a decade ago to over $89 billion now, says Hedge Fund Research. Activists' clout could expand even more as they go global. (Daniel Loeb has tried to shake up Sony (SNE), for example.) But funds' thunder might quiet if their returns shrivel, a possibility that reflects a nagging doubt about their performance. The activists have done well in a rising market. The sterner test will come when they have to work their magic in a falling one.

--Geoff Colvin

1.Elon Musk

Elon Musk

Tesla, SpaceX, SolarCity

--Cultural impact
--No. 1 revenue gainer
--No. 2 stock price gainer
It is no Secret that Elon Musk is a triple threat: The co-founder of PayPal has gone on to disrupt aeronautics with Space Exploration Technologies, known as SpaceX; shake up the auto business with Tesla Motors (TSLA); and retool the energy sector with SolarCity (SCTY). (He is CEO of the first two companies and chairman and largest shareholder of the third.) But 2013 was an especially notable year for Musk, as investors and consumers wholeheartedly embraced his ideas and vision. After a rocky start a decade ago, Tesla has emerged to become the world's most prominent maker of all-electric cars. Revenue at Tesla is up more than 12-fold for the first three quarters of the year, and the company is on track to top $2 billion in sales in 2013. The stock is up more than fourfold year to date, and that's after giving back some gains when recent vehicle sales missed some analysts' estimates. (A series of troubling car battery fires has not helped.) And just as SpaceX has helped reignite interest in space exploration, Musk's plans for a "hyperloop" between San Francisco and Los Angeles got Americans buzzing about ultra-high-speed transit when Musk released his design plans in August. Musk's creations have already made him tremendously wealthy -- Bloomberg Wealth says he is worth $7.7 billion -- but it is his audacity and tenacity that make him Fortune's Businessperson of the Year.
--Adam Lashinsky