Force Quit is an extension that adds a ‘Force Quit’ button to the top panel of gnome shell, the UI of Gnome 3. Clicking the ‘x’ icon from the left of the gnome-shell panel changes the cursor into a ‘x’. Then, click over a non-responding application to kill it instantly.

This extension employs ‘xkill’ on the backend.

Installation:
From Gnome Shell Extensions Directory:
https://extensions.gnome.org/extension/102/force-quit/

Or Manually:

Download:
cd ~/.local/share/gnome-shell/extensions
git clone https://github.com/xtranophilist/gnome-shell-extension-force-quit.git
mv gnome-shell-extension-force-quit/ force-quit@xtranophilist

Restart Gnome:
Alt+F2 to open run command prompt
Enter r

Enable ‘Force Quit Extension’ from Extensions from gnome-tweak-tool

Git Repo:
http://github.com/xtranophilist/gnome-shell-extension-force-quit/

Superpiffer has created a package for archlinux in AUR (https://aur.archlinux.org/packages.php?ID=55879)

If it doesn’t work on your system, maybe you don’t have xkill. jjmarin on GSE says “In fedora you need to install the package xorg-x11-apps in order to get the xkill”.