After doing a cast for the first two Mass Effect games, it seemed appropriate to cast the third one as well.
I will be combining both casts of the first two, with some changes/additions. The reason for the changes is because one seemed to be too big for the small screen and one just didn't fit the role.
Here is the cast.
David Boreanaz as Shepard
Colin Donnell as Kaiden Alenko
Eliza Dushku as Ashley Williams
Joe Manganiello as James Vega
Alan Tudyk as Garus Vakarian
Morena Baccarin as Liara T'soni
Adam Baldwin as Urdnot Wrex
Rooney Mara as Tali Vas Normandy
Seth Green as Jeff "Joker" Moreau
Keith David as David Anderson
Yvonne Strahovski as Miranda Lawson
Corey Reynols as Jacob Taylor
Aziz Ansari as Mordin Solus
And if you need convincing:
Lucy Lawless as Samara
Julia Stiles as Jack
Steve Downes as Urdnot Grunt
Tricia Helfer as EDI
Rhys Ifans as Thane Krios
Max Martini as Zaeed Massani
Rila Fukushima as Kasumi Gato
Bruce Campbell as Armando Bailey
Will Yun Lee as Kai Leng
Hisham Tawfiq as Javik
Keith Szarabajka as Harbinger
Richard Jenkins as Udina
Patrick Dempsey as The Illusive Man