A Manager was any of a set of specialized components of the Mac OS operating system, including those that comprised the Macintosh Toolbox. Each of these Managers was responsible for handling system calls from applications running on the Macintosh, and could be built into the ROM or be loaded into RAM by the system.

Many of these Managers and their functions have been ported to or re-implemented in the Carbon application frameworks. Some of the Managers included in various versions of the Mac OS include:

• Code Fragment Manager (CFM)
• Component Manager
• Data Access Manager
• File Manager
• Mixed-Mode Manager
• Resource Manager
• Scrap Manager
• Sound Manager
• Speech Manager
• Window Manager