The Prince of Persia and Judge Dredd actor plays Corlys Velaryon in the fantasy prequel series which is due to begin on Sky Atlantic on Monday, but said that just because it was linked to a hugely successful show it didn't mean that House of the Dragon could be sure of being received in the same way.
Read more: How to watch House of the Dragon in the UK
Speaking about previous failed Game of Thrones spin-off, Bloodmoon, which was shelved before ever airing as a cautionary tale, he told The Guardian that he had originally been eying a role in that, too.
He said that he had met an actor while at another job who had been filming the pilot for the spin-off and when he had expressed an interest in joining the cast, she told him it was about to take off massively and that there would be no end of roles to go for.
Bloodmoon never made it to TV and Toussaint said: “And they had spent somewhere like $30m on that. I’d love to believe that something’s too big to fail, but nothing is.”
Toussaint, 57, has previously addressed the racism he has faced from some Game of Thrones fans and spoke to The Guardian about the absurdity that his casting as Corlys Velaryon was the thing that anyone would find most unrealistic about the dragon-filled fantasy series.
He said: “I mentioned this the other day to my white friends, and they were all like: ‘Oh my God!’ But when I mentioned it to my friends of colour, they were like: ‘Well, we knew that was coming,’ you know? We were just: ‘I wonder how long it will take?’ And it was minutes. None of us were surprised.
“It’s funny, because you go: ‘You don’t have a problem with flying dragons, but a Black guy who’s a nobleman?’ But I don’t hate. Listen, those people are best left to themselves. To those things.”
House of the Dragon begins on Monday, 22 August at 2am on Sky Atlantic and NOW TV with the US broadcasting simultaneously on Sunday evening.
Watch: House of the Dragon cast speak ahead of show's release