ICQ was started in 1996 by Israeli company Mirabilis, which AOL bought in 1998. ICQ grew to 100 million registered users at one point, at least according to a 2001 release from Time Warner, which had bought AOL a year earlier in a famously doomed merger. AOL sold the service to Digital Sky Technologies, the firm that owned VK, then known as Mail.ru, in 2010.
I would have joined sometime in '96 or '97 (UIN 268078). I switched to AIM sometime in college a few years later, largely because my account was successfully phished away from me. It was a great way (or at least seemed like one at the time) to keep in touch with some people back in the days before social media was a thing. I have no illusions that it has existed as anything other than a brand for many years, but its official passing is notable nonetheless.