Configure Auto Login with Regedit Windows 8 8.1 on Domain

HKLM\Software\Microsoft\Windows NT\CurrentVersion\winlogon

AutoAdminLogon = 1 (String Value Key) (0 means off, 1 means automatic)
DefaultUserName = Username (String Value Key)
DefaultPassword = Password (String Value Key)
DefaultDomainName = domain.com (String Value Key) (Only needed if this computer has joined a domain)

Reboot

Note:
To bypass AutoAdminLogon, hold down the Shift key as Windows 8 initializes.