Those Angry Birds are just unstoppable. News came out this morning that Rovio, the company behind Angry Birds, has raised a whopping $42 million from investors.

The funding round was led by Accel Partners, a venture capital firm that was worked with companies such as Facebook and Groupon and Atomico Ventures, which was created by Skype co-founder Niklas Zennström. According to Rovio, leading super angel fund Felicis Ventures also participated.

Zennström will be joining Rovio’s board. “Angry Birds is one of the fastest-growing online products I’ve seen, growing even faster than Skype, and the company has done a brilliant job of extending it across different platforms and merchandise. I’m really looking forward to joining the board, and helping the team to fulfill its ambitions,” he said.

Mikael Hed, CEO and co-founder of Rovio, said, “Angry Birds will continue to grow, and we aim to create more similar success stories. We will strengthen the position of Rovio and continue building our franchises in gaming, merchandising and broadcast media.”

The popular game is planning a move to Facebook in May and already dominates the screens of mobile devices and is available on Macs, PCs and the PlayStation as well.

Related Stories:

Angry Birds flying to Facebook; Rumors Addressed

Angry Birds, Facebook and you: Understanding your addiction

Angry Birds, Facebook to team up in May