The wife. Kids are 5 and under, hence $100 a year is the same as $100,000 a year to them at this point ("a really big number"). I'll probably share it some day when they are older. Definitely will share it if they are curious about careers and what Daddy does all day. Both kids already understand the money supply chain. Work/sacrifice/not spend time with kids --> money --> satisfying wants/needs --> save what is left.
I will discuss general round numbers with close friends in the industry to get an idea of where I am and where they are. One of us could hire the other if we like the other and their salary isn't up to market. I like to remind people that I'm a corporate whore and will go with the highest bidder offering the best terms.
I have told maybe 3-4 people exactly what I make, but that was basically a predecessor to salary negotiations - as in "I make X, I would need at least X+6000 to make me move to your firm. Do you think it would happen if I came in for an interview?". Helps prevent wasted time for me and for the other person if there is no way they can match my salary demand.
Extended family - bros, in-laws etc have no idea what I or DW make. I think one BIL may have seen our salary info on some immigration forms for financial sponsorship. But those were W-2 salaries, hence didn't include a lot of pre-tax deductions like 401k, health ins, child care, etc.
My general rule of thumb is that I keep the level of detail appropriate for the situation. I have no problem telling people our household income is in the very low six figures. But usually don't get more specific than that unless there is a reason.