Hu Fuming (胡福明), author of the famous May 1978 article “Practice is the sole criterion of truth” (实践是检验真理的唯一标准), passed away on Jan. 2, 2023 of Covid. (Probably his death certificate will reflect some other cause.) It was revolutionary for the claim it implicitly rebutted: that what Mao (or any of the classical Marxist authorities) said was the criterion of truth. I was in China at the time as a student and I remember how exciting it was for this to come out. Remember that this pre-dated the Third Plenum of the 11th Central Committee as well as Democracy Wall. Pretty bold stuff.
Here’s a nice essay on the background to the piece, as well as the original Chinese text and a translation, by David Cowhig: https://perma.cc/8928-9DBK