Suggestions by @bri_c

Terry Chen

as Professor Kaori in Fourth Wing

Idris Elba

as Tairneanach (Tairn) in Fourth Wing | Iron Flame | Onyx Storm

Will Poulter

as Brennan Sorrengail in Fourth Wing | Iron Flame | Onyx Storm

Gregg Sulkin

as Brennan Sorrengail in Fourth Wing | Iron Flame | Onyx Storm

Cameron Monaghan

as Brennan Sorrengail in Fourth Wing | Iron Flame | Onyx Storm

Elle Fanning

as Andarnaurram (Andarna) in Fourth Wing | Iron Flame | Onyx Storm

Millie Bobby Brown

as Andarnaurram (Andarna) in Fourth Wing | Iron Flame | Onyx Storm

Tatiana Maslany

as Mira Sorrengail in Fourth Wing | Iron Flame | Onyx Storm

Pheobe Tonkin

as Mira Sorrengail in Fourth Wing | Iron Flame | Onyx Storm

Hunter Doohan

as Aaric in Fourth Wing | Iron Flame | Onyx Storm

Gavin Casalegno

as Aaric in Fourth Wing | Iron Flame | Onyx Storm

Millicent Simmonds

as Jesinia Neilwart in Fourth Wing | Iron Flame | Onyx Storm

Josephine Langford

as Catriona cordella in Fourth Wing | Iron Flame | Onyx Storm

Katherine Langford

as Catriona cordella in Fourth Wing | Iron Flame | Onyx Storm

Dove Cameron

as Catriona cordella in Fourth Wing | Iron Flame | Onyx Storm

Theo James

as Professor Emetterio in Fourth Wing | Iron Flame | Onyx Storm

Keri Russell

as General Lilith Sorrengail in Fourth Wing | Iron Flame | Onyx Storm

Maya Hawke

as Quinn in Fourth Wing | Iron Flame | Onyx Storm

Ross Butler

as Bodhi Durran in Fourth Wing | Iron Flame | Onyx Storm

Emma Myers

as Sloane mairi in Fourth Wing | Iron Flame | Onyx Storm