John Horton Conway died, as reported by The Grauniad — due to COVID-19, not that it really makes a difference in the grand scheme of things. Conway was one of the greatest mathematicians of the 20th century, and, by all accounts, a fascinating man as well. I recommend reading Siobhan Roberts' John Horton Conway: The Most Charismatic Mathematician in the World for starters; if you're keen on learning more I also highly recommend her biography of Conway, Genius at Play: The Curious Mind of John Horton Conway.
We've lost a great mind and a great man today. Rest in peace.