Glossary
taskhostw.exe
The Windows process that hosts DLL-based scheduled tasks (COM handler actions), started by the Task Scheduler service.
taskhostw.exe, "Host Process for Windows Tasks", runs from C:\Windows\System32 and loads the DLLs behind COM handler actions, usually as a child of the svchost.exe instance hosting the Schedule service. Earlier versions of Windows used taskhost.exe (Windows 7) and taskhostex.exe (Windows 8) (Shlomi Boutnaru's process notes).
Executable (Exec) actions are started by the service directly, not by taskhostw. A taskhostw.exe outside System32, or loading a DLL from a user-writable folder, deserves attention.