Thank you for letting us know, Itzik; I am so sorry to hear this news.

Deror and I worked on many Wikimanias together, as planners and as members of the steering committee, but we spent perhaps the most time together on the program for Wikimania 2017. For that conference, Deror put the hundreds of submissions we got into wikitables by hand, reviewing and scoring them all. We had gotten a lot more submissions than we expected, and so we spent a lot of time talking about how many of the talks we could accept. Why not just hire more rooms at the venue? Deror would say. He always wanted to take as many as we could.

In this way and in so many other ways, Deror was a maximalist. He wanted to know all he could, see everything he could, and share everything he possibly could with others. When he took me on a tour of Haifa and Jerusalem, I came away sharing some of the profound wonder and love he had for these places. When we met up elsewhere in the world for Wikimania, going on other people's tours was always at the top of the list for Deror -- he wanted to learn about the home turf of other Wikipedians as much as he wanted to share his own. He also shared his photos, his belief in editing Wikipedia, and his profound desire to bring people together at events and trainings. A Wikipedian with many, many thousands of edits, he always said he was bad at computers. But this never seemed to discourage him much. 

Funny, enthusiastic, argumentative, joyous Deror: your curiosity and desire to learn things knew no bounds. I'm lucky to have known you, Wikimedia was lucky to have you, and you will be very missed. Condolences to his family, and to his many friends. We will remember you with love and the hope of carrying on your commitment to open knowledge and spirit of adventure in the world.   

-- Phoebe