Robert Downey Jr.’s camp is denying widespread speculation that he is the anonymous commenter who has been spreading dark Hollywood rumors on the blind item website Crazy Days and Nights.

Over the past month an anonymous commenter who goes by the name "Himmmm” has been dropping bombshells about bad behavior in Hollywood, detailing alleged starlet call-girl rings, pedophilia and rape.

Several clues provided by the anonymous poster as to his identity, particularly that they had almost let addiction ruin their Hollywood career, led other commenters and websites to speculate that Himmmm was Downey Jr., who had publicly battled addictions for years.

But this week, Alan Nierob, a rep for Downey Jr., is trying to put those rumors to rest.

“Of course he isn't,” Nierob told Fox411.com when we asked whether his client was Himmmm.

Nierob added that it will be up to the actor’s legal team to decide whether to press charges against the sites who are hosting the commenters who allege Downey Jr. is the anonymous commenter.

Crazy Days and Nights is a website that deals in blind items about celebrities, mostly sent in from anonymous tipsters. Likewise, commenters can also be anonymous. Last month the site ran this blind item detailing the abusive relationship of a young starlet in Hollywood:

“This former B list television actress who was on a really big hit network show just a couple of years ago now just seems to float mindlessly and flit between boyfriends. She comes from a broken home and abusive home. Her dad used to beat her and get into bed with her.

Her mom just let it happen because she was being beaten herself and did not want to provoke. Well, now the actress who is still very young only seems to date boyfriends who are abusive and willing to hit her. Her last boyfriend (former A list athlete with B list name recognition) was so scared that he would kill her if he  [if] he broke up with her. Her new celebrity boyfriend does not punch nearly as hard but seems to love it. Probably getting out his anger because he is closeted.”

After several visitors guessed that the actress in question was “Heroes” star Hayden Panettiere a commenter named “Himmmm” said the actress was indeed Panettiere and weighed in with detailed information.

A rep for Panettiere did not return calls for comment.

More recently Himmmm went after actors Ryan O’Neal and Kirk Douglas.

In response to a blind item about an older actor who slept with a teenaged actress Himmmm wrote:

“Ryan F**khead Oneal. And if there's a hell - they have a special suite awaiting him. Not just for this, but for the HELL he's caused me and so many others. I'll not name his victims, but his filmography and dating history should show that clearly. I learned to let the hate out of my heart many years ago, but some people deserve to reap what they sow. Ryan Oneal is the f**king antichrist. I know, believe me.”

O'Neal's rep Arnold Robinson told Fox411.com: "That is a ridiculous and completely untrue assertion."

Further speculation that Himmm was Downey Jr. came when Himmm claimed that he knew that the actor Kirk Douglas had raped Natalie Wood. He provided as proof the fact that he worked with Wood’s daughter, Natasha Gregson Wagner, on a film in the late ’90s, and he provided her correct phone number.

“Like her mother, Natasha is an amazing woman and amazing actress who is a great person in every way,” Himmmm wrote. “I know a lot of you have speculated that I’m some nobody nut-case pretending to be someone else. Pretending to be a movie star when in fact I’m not. I think that’s kind of hilarious. But if you want to call Natasha and ask her the name of the male actor she co-starred with in a movie with Heather Graham, then go for it. Call her at home if you want to but be polite. Her number is: XXX-XXX-XXXX And remember, she’s NOT in on this so don’t blame or interrogate her.”

Downey Jr. appeared in the James Toback film "Two Guys and A Girl" with Heather Graham and Wagner in 1997.

A rep for Douglas did not return calls and emails for comment.

Fordham media studies professor Paul Levinson, who writes extensively on the way social media has changed the way people interact, told Fox411.com that contrary to popular belief, anonymity online does not mean that people are necessarily telling the truth.

“I wouldn’t trust anyone who hides behind a pseudonym,” Levinson, the author of “New New Media” said. “It allows them to lie and to say whatever they please without any repercussions.”