ProgressBar
The MahApps.Metro ProgressBar is like the built-in progress bar but, of course, restyled.
The upper two bars are the ProgressBar with different progress states. The third bar has IsIndeterminate set to True
MetroProgressBar
MetroProgressBar is an alternative and simpler style. Instead of creating a normal ProgressBar use:
<Controls:MetroProgressBar />
Its indeterminate state looks like a ProgressRing but not circular.