Guessing who might replace Steve Ballmer has always been something of a parlor game for Microsoft Corp. watchers.
And now that Ballmer's departure is pending, the answer to who will follow him remains as much a mystery as ever. There is no single clear successor to a lightning rod of a leader who remains one of the most identifiable CEOs in the country.
The once-deep bench of likely successors has been largely drained in the past several years. Some have left for leadership positions at other companies, such as former sales chief Kevin Johnson, who has been chief executive of Juniper Networks for the past five years, and Stephen Elop, who led Microsoft's Business division before becoming chief executive of Nokia.
Other potential Ballmer successors have walked away from the company or been pushed out the door. Robbie Bach, who ran Microsoft's Entertainment and Devices division, and J Allard, who led that group's design effort, were both possible chief executive candidates. But they both left the company in 2010, after disagreeing with Ballmer over pursuing a tablet-computing device that Microsoft decided to shelve.
More recently, Steven Sinofsky, a polarizing leader who ran both the Office and Windows teams in his 23 years at Microsoft, left the company last November, after a falling out with Ballmer.
So who's left among the internal candidates to run Microsoft?
Probably the executive at the top of that list is Kevin Turner. And while the voluble chief operating officer certainly knows how to manage the company, he doesn't have the technical background that might important to the board as they select the next leader. He joined Microsoft in 2005, after serving as president and chief executive of Sam's Club.
Another internal candidate whose name still gets mentioned is Satya Nadella, executive vice president of Microsoft's Cloud and Enterprise group. Nadella runs a group that continues to churn out growth and profits.
Tony Bates, the executive vice president of Microsoft's Business Development and Evangelism group, is the latest rising star in the executive ranks at the company's headquarters in Redmond, Wash. Bates joined the company after Microsoft bought Skype, the video conferencing company that he ran, in 2011. He's since been given more power in a recent reorganization, where he oversees the company's relationships with computer makers, software partners and developers. He also leads Microsoft's corporate strategy team.
Given the short bench of CEO successors, Microsoft's board will no doubt look externally as well. Both Johnson and Elop are likely to be on the list of candidates they'd call. Juniper has thrived under Johnson, who announced plans to retire from the company last month, as networking gear sales have gained from the flood of Web traffic generated by mobile devices. Nokia, meanwhile, continues to struggle under Elop, who placed a big bet that has not panned out on the Windows Phone operating system to run the company's devices.
One other former Microsoft executive who could be in the mix: Paul Maritz. The former Windows boss, who continues to have a following in Redmond, left Microsoft more than a decade ago. Since then, he's served as chief executive of VMware Inc., an arch-competitor of Microsoft's in virtualization technology. He left that job and joined Pivotal, a Web-services company, this year as its CEO.
Another outside candidate that might get consideration is Reed Hastings, the chief executive of Netflix Inc. Hastings stepped down as a Microsoft board member last year, saying then that he wanted to focus on Netflix. But some have speculated that Hastings could be next in line for the CEO post because he both understands Microsoft's culture and has expertise in consumer services, an area where Microsoft sometimes stumbles.
Explore further: At a Glance: Microsoft CEO Ballmer's ups and downs