Yes, many. Every WebKitGTK based browser [1] will use JSC, so that includes the "GNOME Web" web browser, Midori, and a host of smaller niche browsers.

[1] https://webkitgtk.org/

Neat. Konqueror uses a different engine, right?

It can. Historically Konqueror used KHTML, however, the default has been changed to QTWebEngine, which is based on Blink i.e. Chromium.

It also supports (supported?) rendering using WebKit, or, you can manually change back to KHTML. However, all recent versions of Konqueror default to WebEngine. https://wiki.debian.org/Konqueror