Good, lightweight GUI-based process monitor for Linux

Look at htop. It's light and it'll do what you want. Yes, it does launch in a console, but you can interact with it using the mouse, it's colored, it's live/animated, you can click on column headers to sort, scroll with the mouse, and anything else you care to try.

There's Linux Process Explorer, a process management tool which seeks to mimic the functionality of Process Explorer for Windows.

Most GUI distros include a basic process management tool among their default system tool set.

So here is what I finally found, LXTask.

• Lightweight, simple
• Monitors processes
• Can kill processes
• Real GUI

There is also the GNOME system monitor, which also displays the process commandline. It is much more resource hungry though...