Use Parseltongue
Speak to the door in snake language
If you are not a Parselmouth, you cannot open it normally
Ask a Parselmouth to open it for you
Use the correct Slytherin password if the door is a common room entrance rather than a chamber door
Use Parseltongue
Speak to the door in snake language
If you are not a Parselmouth, you cannot open it normally
Ask a Parselmouth to open it for you
Use the correct Slytherin password if the door is a common room entrance rather than a chamber door