The cast of "The Walking Dead" spoofed the hit zombie show while a host of celebrities manned phone lines Thursday as America's Red Nose Day raked in $30.7 million for needy children.

Norman Reedus, Andrew Lincoln and many other stars of AMC's record-breaking series parodied their characters in one of a series of video vignettes which raised a laugh during the second annual NBC comedy telethon.

Mila Kunis, Ashton Kutcher and Minnie Driver were the biggest names among more than a dozen stars in the studio who answered members of the public calling in with pledges.

Craig Ferguson, the Scottish-born veteran of US late night TV, was master of ceremonies during the two-hour live broadcast at Los Angeles' Universal Studios.

"Remember, if it's not funny it doesn't matter -- you're laughing to save lives," the funnyman told the audience during one commercial break.

More than 50 stars of film, television and the music world took part in the event, which raises money for children in America and overseas.

One of the show's highlights was a pre-recorded parody ballad which saw "Machete" star Danny Trejo, Hollywood A-lister Steve Buscemi and Iwan Rheon -- evil nobleman Ramsay Bolton in "Game of Thrones" -- cast aside their tough guy images to croon: "Why can't I be a part of Red Nose Day?"

There were pre-recorded sketches from Paul Rudd, Sarah Silverman, Tracy Morgan, Jordan Peele and Margot Robbie, who reprised her "naked in a bathtub" spot seen in Wall Street comedy "The Big Short."

A skit making fun of the charity appeal trope which sees numerous stars saying one line or even just a few words each featured Zac Efron, Julianne Moore, Ellen DeGeneres, Emma Watson, Liam Neeson, Bill Gates and Bono.

Julia Roberts and rapper Ludacris visited impoverished, sick and hungry American children, while Jack Black updated viewers on a street child in Uganda who was finally getting an education thanks to cash from the previous year's appeal.

The music was provided in pre-taped segments from Elton John, who belted out his ballad "A Good Heart," while country musician Blake Shelton sang "Saviour's Shadow."

The American Red Nose Day, launched last year, emulates a British version which has raised more than $1 billion over 30 years.