The announcement for the final members comes at this time as production for It: Chapter Two is expected to begin next month.

'Old Spice Guy' to movie star

Mustafa has had smaller roles in movies such as a minor role in "Horrible Bosses" but is best known as the ‘Old Spice Guy’ in which he played the spokesman for Old Spice Body Wash in their 2010 commercials.

The casting of Isaiah was announced by actor Chosen Jacbobs, who played the young Mike Halon in IT 2017 when he posted an Instagram photo of Mustafa with the caption, “You’re one of us now”

Isaiah is no stranger to staring in adaptations, however, as his most recent role was playing Luke Garroway on Freeforms TV show "Shadowhunters", [VIDEO] based on the best-selling book series "The Mortal Instruments".

The last season of the show has already been filmed and is also set to be released in 2019. Following the show's recent and shock cancellation, Mustafa, will hopefully be returning to feature in the special two-hour long episode finale which is yet to be filmed. But, with his casting in this movie, it is unclear as to whether he will be available to feature or if the filming schedules with conflict with each other.

In his own Instagram post, Isaiah, expressed his excitement about joining the cast, thanking the production companies from "Shadowhunters" and "IT" for making the “stars align,” making fans hopeful that he will be appearing in both projects.

While in the first movie, Mike's role as the resident historian of the group has instead been given to Ben, he will return back to his original role and stay in Derry to be the librarian, where he can further establish the history of Pennywise.

Mike will be walking a darker path in the second Chapter

This means that with Isaiah taking on the role of Mike Halon in this movie, he will be the only member of the gang to stay in Derry while the others move away. So, that he can also be the one to inform the rest of the group if Pennywise does return. In which, they must honour their pact made in the last movie, to return and finally defeat Pennywise once and for all.

Director, Andy Muschietti, has previously hinted that Mike in this movie will follow a darker path than the audience has seen on screen before. He states that as Mike is a major character, being the one to bring them all back while staying in the Derry trying to collect all the knowledge about Pennywise. It will lead him to turn to drugs as a coping mechanism with Muschietti claiming: “I want him to be a junkie actually.’

Over the past couple of months, actors who will be playing the adult counterparts of the children who made up ‘The Losers Club’ in the first IT movie have been announced.

Isaiah will be acting alongside, James McAvoy as Bill Denbrough, Jessica Chastain as Beverly Marsh, James Ransone as Eddie Kaspbrak, Jay Ryan as Ben Hanscom, Bill Hader and Richie Tozier and Andy Bean as Stanley Uris. As for Pennywise, Bill Skarsgård will be reprising his role as the demon clown to terrorise 'The Losers Club' all over again as adults.

"IT: Chapter 2" is set to arrive in cinemas on September 6, 2019.