https://techcrunch.com/2018/04/11/is-zuckerberg-under-oath-c...
John M Poindexter was one who was convicted of lying to Congress: https://en.wikipedia.org/wiki/John_Poindexter#U.S._executive...
[1] https://www.economist.com/united-states/2018/12/13/michael-c...
It's one of the reasons Cohen is in prison, isn't it?
It is illegal to lie to Congress (unrelated to whether you're under oath or not), but I can think of very few examples where there were real ramifications for it.
Sure you're not thinking of Manafort? I don't think Cohen had a plea deal, and I don't think he was charged with lying to the FBI. Manafort and Flynn did, and Manafort I think was the one that then broke the deal. There's a lot of crimes to keep track of.
I guess it depends on what you mean by real ramifications as it's being served concurrently but Cohen is serving two months for lying to Congress, a charge he plead guilty to.
I just want to point out that "testified in-front of Congress" seems to have no relation to the truth of any statement. I don't recall the last time (if ever) there have been legal ramifications for lying in front of Congress.
Zuckerberg also testified that shadow profiles don't exist and that users can always remove their personal information from Facebook (they do exist, and you can't). James Clapper testified that the NSA doesn't "wittingly" surveil hundreds of millions of Americans (they do, very "wittingly").