GNOME System Monitor

GNOME System Monitor is a GNOME process viewer and system monitor with
an attractive, easy-to-use interface, It has features, such as a tree
view for process dependencies, icons for processes, the ability to hide
processes that you don't want to see, graphical time histories of
CPU/memory/swap usage, the ability to kill/renice processes needing root
access, as well as the standard features that you might expect from a
process viewer.