Megan Fox has been announced as Zooey Deschanel's replacement on US comedy New Girl, leaving fans of the show scratching their heads.

Fox will fill in for Deschanel for half of season five while the show's star is on maternity leave.

The Transformers bombshell will play a "straight-shooting pharmaceutical sales rep" who rents Deschanel's character Jess' apartment while she is away on jury duty.

While the actress is not known for her comedy chops, executive producer Liz Meriwether said the part was actually written with Fox in mind.

"It's insane to me that such a gorgeous person can be so funny, but I guess we just all have to accept it," she said.

"I've been a fan of her comedic skills since This is 40, and I'm so excited to have her on the show."

Deschanel's trademark wit and cheek is the bedrock of New Girl, and it will be interesting to see how Fox fills the void left by her character.

The news was met with mixed reaction from fans, with some threatening to "boycott" the show once Deschanel went on maternity leave.

Despite being nominated for five Golden Globe and Primetime Emmy Awards, New Girl's US audience has more than halved since its first season.

Megan fox is just going to ruin New Girl— Alex Adams (@Dancelex) September 20, 2015

MEGAN FOX IS REPLACING ZOEY DESCHANNEL ON NEW GIRL OH MG GOD NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO— renata ✨ (@renatadeleonp) September 20, 2015

Wtf Megan fox is going to replace Jess in New Girl while she's on maternity leave........ LAMEEEESKIIIIS— bleh (@biphmm) September 20, 2015