How to Hide a Process

Processes can be hidden in both Windows (from the Ctrl+alt+delete menu) and Linux (from ps and top).
In windows:
Programs listed as services are not shown up.
Example Borland c code:

Example delphi code:

Linux process hiding:
Hiding from logs (Although i see few legal situations where you would need to hide a process you ran). You can change the name of a process so it looks like another process. eg (From Phrack);

“Basically, this program waits for a key-stroke and then exits. But, while it’s waiting, if you were to lookup the process it would show the name as being “rn”. You’re just actually re-writing the argument list of the spawned process. This is a good method of hiding your process or program names. Its a good idea to use this method in any “rogue” programs you might not want to be discovered by a system administrator.”