You're a businessman, Mr. Wayne. You know that saying something doesn't make it so. I'll need a contract, inked in your blood, of course. Oh, you're modern, rational, well-educated, a civilized man of peace and moderation. Of course you don't believe in Satan, but that doesn't matter. Satan believes in you. He knows there's a beast inside of you.
This character is a fictional representation of Aleister Crowley, a real person. More information on this person can be found at Wikipedia.org.
Aleister Crowley was portrayed by Jonjo O'Neill.
Trivia
The Devil in Crowley's mansion
In the episode Cilla Black, Martha Kane was led into a room full of Satan worshippers in Crowley's mansion, leading to her witnessing the "Devil" himself; a man with an animal head and multiple eyes. In the episode Julie Christie, Crowley appears behind Thomas Wayne and says that he knew there was a beast in his soul, and, Thomas has met the devil (it was more of a metaphorical meeting). It is likely that the being seen in Crowley's mansion by Martha is a result of drugs or booze being used in his mansion.
There are implications that Crowley and Jason Ripper are in a romantic and/or sexual relationship.[1]
You're a businessman, Mr. Wayne. You know that saying something doesn't make it so. I'll need a contract, inked in your blood, of course. Oh, you're modern, rational, well-educated, a civilized man of peace and moderation. Of course you don't believe in Satan, but that doesn't matter. Satan believes in you. He knows there's a beast inside of you. 
