In my opinion, probably not. But if you watch the video below, you’ll see a fair number of similarities in terms of mannerisms and voice between Heath’s Joker and Tom Waits. After doing a youtube search of interviews done with Tom Waits, this was the only video that I could find where he had any similarity other than his voice. Besides, this interview was done in 1979, the same year Ledger was born. I guess Heath Ledger could have been a big Waits fan and seen even the more obscure interviews, but that might be a bit of stretch.