Since this trend looked fun, here is my take on voice actors that could give life to the primarchs.
by request:
Charles Dance: Game of Thrones season 2 asy Tywin, the Witcher 3 as emperor Emyhr
Sunil Malhotra : From the Legend of Vox Machina, as Gilmore
Fred Tatasciore: From the animated transformers Series as Megatron
Jason Momoa: From the second season of See as Baba Voss
Leman Russ is voiced by Vox In The Void Pal, sorry for the mistake
Steve Downes is from a Youtube video of his, but you might know him as the voice of Master Chief
Malcolm McDowell is from the 3rd season of Castlevania, as Death.
James Callis is also from Castlevania as Alucard, this particular quote is from season 1.
Travis Willingham from the English dub of the 2003 Fullmetal Alchemist, as Roy Mustang
Patrick Seitz is from World of Warcraft, I think this line is from Pandaria, he plays Garrosh Hellscream
Chris Metzen plays lots of characters in WoW, this is from the Launch trailer of the Legion expansion, as Varian Wrynn
Paul Nakauchi is from Diablo 3, as Malthael
Henry Cavill is from the first season of The Witcher, as Geralt
Josh Brolin is from InfinityWar, as Thanos
Matt Mercer is from the second campaign of the D&D streaming show Critical Role, as Lucien
Lance Reddick is from Destiny 2, as Commander Zavala
Liam O’Brien is from WoW again, from a video called Harbingers: Illidan, as Illidan
Troy Baker is from Far Cry 4, as Pagan Min
0:00 The Lion - Charles Dance
0:52 Fulgrim Sunil Malhotra
1:41 Perturabo - Fred Tatasciore
2:22 Jaghatai Kahn - Jason Momoa
3:34 Leman Russ - A Vox in the Void
4:20 Rogal Dorn - Steve Downes
5:01 Konrad Curze - Malcolm McDowell
5:55 Sangunius - james Callis
6:47 Ferrus Manus - Travis Willingham
7:48 Angron - Patrick Seitz
8:48 Roboute Guilliman - Chris Metzen
9:46 Mortarion Paul Nakauchi
10:47 Horus Lupercal - Henry Cavill
11:18 Magnus the Red - Josh Brolin
12:07 Lorgar Aurelian - Matt Mercer
12:59 Vulkan-Lance Reddick RIP Legend
13:46 Corvus Corax - Liam O’Brien
14:39 Alpharius Omegon - Troy Baker