L is Monty Burns

If L were old and turned to evil, he would be Monty Burns!

The evidence:

1. Skinny, delicate hands, bags under eyes, poor posture, odd way of holding things

2. Eccentric billionaire who values his privacy ("Release the hounds!")

3. Has a caretaker (Wattari/Smitthers) who handles all of his daily mundane needs because practical matters are beneath/beyond him

4. Tendency to watch suspects/workers on video monitors

5. Ambivalent morals & Would take candy from a baby!

...this isn't much of a stretch as they are both INTPs and awesome characters ^_^