I very much like to remember him by pasting below a picture taken during a free-fall flight - a tale-telling proof that he wouldn't resign to his life challenges. Notice the Newtonian apple above him.
The contributions of Hawking to our understanding of the universe are very significant. The most well-known among those was on the thermodynamics of black holes, with his prediction that black holes can radiate electromagnetic radiation and even evaporate due to the resulting energy loss; but his research encompassed much more, from his early work of 1970, when he demonstrated that assuming general relativity and the cosmology theory of Friedmann the universe must have originated in a singularity, to later very significant contributions to research in quantum gravity.
Hawking also wrote several science popularization books, participated in shows, and was quite active in science outreach. He held very pessimistic views on humankind, which can be summarized in his prediction of our (early) extinction. I hope he was wrong on that one, or if you will I hope I will never know.
[*] In journalistic jargon, a crocodile is an obituary written before the passing away of the subject.
Tommaso Dorigo is an experimental particle physicist who works for the INFN at the University of Padova, and collaborates with the CMS experiment at the CERN LHC. He coordinates the European network AMVA4NewPhysics as well as research in accelerator-based physics for INFN-Padova, and is an editor of the journal Reviews in Physics. In 2016 Dorigo published the book “Anomaly! Collider physics and the quest for new phenomena at Fermilab”. You can get a copy of the book on Amazon.