The account hijacker appeared to be taunting the actor on Sunday, also posting photos of Kate Upton and a video of "Funny Cats."
Mark Ruffalo, who can be seen as the giant green superhero in Marvel's The Avengers, had his Twitter account hacked on Sunday, resulting in spam messages sent to more than 155,000 followers.
The first suspicious tweet came just before 3 p.m. PT and was followed by a series of posts promoting a website called mylikes.com, which appears to be an ad platform for social media. The hacker also changed Ruffalo's username from its original @MRuff221 to @Mark_Ruffalo.
"The women of hollywood sure have some great boobs. Here are the top 15!" reads one tweet, while another says: "Who has the best booties in Hollywood. Check out the top 15."
"It's kind of hilarious me getting hacked today," Ruffalo apparently responded. "I got to hand it to the hacker. Kind of genius."
"Followers. Hang in there a little longer. I will get back my name and Mruff221," he added.
The hacker later added links to photos of Kate Upton and a YouTube video of "Funny Cats" before signing off. "Sleep Now. I hope you will resolve your passwords," wrote the hacker. "Your account hacked because passwords set very stupid LOL =))"
As for Ruffalo's original account, a fan has apparently registered the name as their own and intends to hold on to it until Ruffalo regains control of his account. The user has sent out a slew of messages assuring followers that they are not the hacker and will return the username to its rightful owner in due time.
A representative for the actor did not immediately return THR's request for comment.