Cassius X puts a period of often-overlooked history into the spotlight – the period when Cassius Clay fought his way to achieving his lifelong dream of becoming World Heavyweight Champion while embarking on a secret spiritual journey.
| Actor | Role |
|---|---|
 Muhammad AliSelf (archive footage) | Self (archive footage) |
| JJim LampleySelf | Self |
 Thomas HauserSelf | Self |
 Robert LipsyteSelf | Self |
| JJerry IzenbergSelf | Self |
| AAttallah ShabazzSelf | Self |
| DDee Dee SharpSelf | Self |