SCP logo, lock mark symbol and warning symbol.

1. SCP logo: The SCP Foundation uses a logo with a yellow circle on a black background and the letters SCP inside to represent the SCP project.

This symbol is often used on SCP files and facilities to alert people to the existence and potential risks of SCP objects.

2. Lock mark symbol: The SCP Foundation uses a lock-shaped mark symbol to indicate the security control of SCP projects.

This symbol is usually used at the door of an SCP device, room, or file to indicate that authorization or special permissions are required to enter.

3. Warning symbol: The SCP Foundation often uses a triangle with an exclamation point placed in the center to indicate potential danger or warning.

This symbol can be used to remind people to stay away from SCP objects, or to warn of their possible effects.