Back on Christmas Day 2016, I remember being suddenly shocked to hear that George Michael died suddenly that day; I didn't hear about this until that night. And he only lived to 53.
Michael Jackson's death was very sudden, to me, as far as I could remember as well.
I won't ever forget the day Whitney Houston passed away. She was the diva who sadly was gone too soon.
Comedian Rik Mayall also suddenly died back in 2014 and I only heard about this after reading a Youtube comment saying something like "RIP Rik Mayall", then I went to his Wiki page. This was really shocking and I used to be a devout fan of him.
Also John Ritter's death (I only heard about this way long after he died; this was during my pre-teen years). I remember John Ritter as Ben Healy, the adoptive father and hero of the Problem Child series, and he was also Clifford the Big Red Dog in the TV series.
I didn't expect to hear that any of these people or Robin Williams died very unexpectantly, nor did I hear how Robin Williams was suffering badly from depression and other things for years.