watchdog.exe is a process belonging to Kwakkelflap Watchdog-O-Matic.
This product monitors critical applications and handles crashes. This process should not be removed to ensure that your system is secure.
Non-system processes like watchdog.exe originate from software you installed on your system. Since most applications store data in your system's registry, it is likely that your registry has suffered fragmentation and accumulated invalid entries which can affect your PC's performance. It is recommended that you check your registry to identify slowdown issues.
Multiple copies of a process in your task manager may indicate the presence of a virus or Trojan. Make sure you always use an updated antivirus software and perform a full scan to identify any such cases.