But more recently, the writer took to Instagram to share a teaser video, along with the news Game of Thrones star Sophie Turner has joined the cast and will voice Princess Charlotte.
“Meet Charlotte - Sophie Turner @sophiet The Prince coming to @hbomax,” Gary captioned the hilarious video, which shows the precious prince getting ready for a Halloween party.
“Hey guys it’s me again, Prince George. Getting ready for a Halloween party downstairs,” George says, before explaining he and his siblings are dressing up as the three little pigs.
But after Charlotte and Louis burst the prince’s bubble by revealing they’ve decided to dress as The Wizard of Oz's Dorothy and Count Dracula, George has a hissy fit before cutting the video short.
“Oh come on, it’s a group costume, guys. It won’t work unless we all do it,” George exclaims, before adding: “Great, so what do I say when people ask me what I’m supposed to be?”
When Charlotte suggests that George tell people he's dressed as Ariana Grande’s pet pig, Piggy Smallz, he berates his sister, before letting out a swear word.
In addition to the Cambridge kids, the series will feature other royals, including Prince Harry (voiced by Orlando Bloom), Kate Middleton (Lucy Punch) and George’s butler Owen (Alan Cumming).
Enthusiastic celebrity fans were quick to comment on the sneak peek video, with Buffy the Vampire Slayer star Sarah Michelle Gellar, writing: “Omg I LITERALLY CAN NOT WAIT.”
Real Housewives of Bevery Hills star Lisa Rinna penned: “GARY!!!!!!!!!” while her co-star Erika Giradi - aka Erika jayne, aka Roxy Hart – added: “OMG” alongside the praise emoji.
Meanwhile, singer Joe Jonas, who is also Sophie’s hubby, shared a screengrab of Gary’s Halloween video teaser on his Instagram Story, along with the caption: “Cannot wait!”
HBO Max head of original content, Sarah Aubrey said in a statement: “We’re so excited to bring the world Gary’s created on Instagram over to HBO Max, where our viewers can discover what his Instagram fans already know — that George can be hilarious, shocking, and surprisingly sweet.
“We can’t wait to see what Gary does with a bigger canvas to paint on than just a 1:1 square,” she added.