Jackson Rathbone is the proud new father of a "beautiful, healthy" baby boy.

The Twilight star and his girlfriend Sheila Hafsadi welcomed their bundle of joy into the world on Thursday morning, US Weekly reports. The baby was born at 9.43 am and weighed 8 pounds 11 ounces.

It is the first child for the actor-and-musician, who is best known for his role as vampire Jasper Cullen.

After announcing the birth via Twitter, the happy couple also revealed their son's name.

"Thank you ALL for the love & support!" Jackson wrote last night. "Sheila & I couldn't be happier to have such a beautiful, healthy baby boy, Monroe Jackson Rathbone VI. [sic]"

Jackson and Sheila announced the pregnancy five months ago, saying they were "thrilled and excited to be expecting their first child."

The couple reportedly met when Rathbone was touring with his band 100 Monkeys.

Meanwhile, Jackson's Twilight co-star Cam Gigandet is expecting a second child with his long-term partner Dominique Geisendorff.

The bundle of joy is expected at the end of the year and will join their three-year-old daughter Everleigh.