Everyone knows Warren Buffett, but three other people who have been making major decisions at Berkshire Hathaway have kept a low profile.

Todd Combs and Ted Weschler manage chunks of Berkshire's stock portfolio and Tracy Britt Cool is Buffett's "financial assistant."

Since being hired in the past four years, the trio, referred to by Buffett as the "Three Ts," have made virtually no public appearances.

That will change Monday morning when they join their boss live at 8 a.m. ET on CNBC for a half-hour slice of "Squawk Box's" annual "Ask Warren," a three-hour marathon that starts at 6 a.m. EST.

For most of the remaining 2½ hours, Buffett will be answering Becky Quick's questions and responding to viewers who have sent in their own questions via askwarren@cnbc.com or the hashtag #AskWarren on Twitter.

Buffett's appearance follows the release of his annual letter to Berkshire shareholders around 8 a.m. ET Saturday.

Tracy Britt Cool

Buffett hired Britt Cool in 2009 when she was just 25 and a recent graduate of Harvard Business School. Buffett met her three years earlier in connection with a group she co-founded as an undergraduate called Smart Women Securities.

In a profile last month, BloombergBusinessweek called the 29-year-old Britt Cool "one of Buffett's most trusted advisers, traveling the country to assist a constellation of companies too small to command her boss's attention."

In a strong endorsement, Buffett said Britt Cool "thinks like I would."

She is chairman of Oriental Trading and Benjamin Moore paints, two Berkshire subsidiaries.

Buffett has dropped negative hints about reports that Britt Cool is being groomed to be his successor as Berkshire's CEO.

Ted Weschler

Weschler had an unusual path to Berkshire. The hedge fund manager paid a total of $5.3 million in charity auctions for two meals with Buffett in 2010 and 2011. "The two men liked each other right away," Fortune reported when Weschler was hired. Buffett "almost apologetically" sounded out Weschler about working for him because Weschler was making so much money with his own hedge fund. After a few weeks of thinking it over, Weschler accepted.

Weschler, 52, has been responsible for Berkshire's growing stake in dialysis company DaVita HealthCare.

Todd Combs

Combs joined Berkshire as a portfolio manager in early 2011 in what was described at the time as an "extended trial" that initially had him handling $2 billion to $3 billion of Berkshire's $100 billion-plus portfolio. He had been running a hedge fund with about $400 million under management.

Combs, now 43, was hired just as longtime Geico investment manager Lou SImpson was retiring. Fortune reported Combs' compensation would be "roughly comparable" to Simpson's: "salary and an incentive compensation plan that gives him a proportion of the amount by which his performance beats the S&P 500 over a three-year period."

Buffett said that was to "get away from the short-term ups and downs of the market when you're paying someone for running money."

—By CNBC's Alex Crippen. Follow him on Twitter @alexcrippen.