I wrote up an article about this which may or may not have been posted...
::cough::
• Cloud Strife: Steve Burton (Cloud in Kingdom Hearts 1&2)
• Tifa Lockhart: Rachael Leigh Cook (Into the West, Las Vegas TV series)
• Kadaj: Steve Staley (Arc in Arc the Lad, Neji Hyuuga in the Naruto animated series)
• Rufus Shinra: Wally Wingert (Big John from Crimson Skies, Remiel from Tales of Symphonia)
• Reno: Quinton Flynn (Raiden from Metal Gear Solid 2, Isaaru from FFX and FFX-2)
• Rude: Crispin Freeman (Albedo from Xenosaga, Siegfried from Soul Calibur 3)
• Yazoo: Dave Wittenberg (Bat from Shin Megami Tensei: Digital Devil Saga, Sora from .hack//Quarantine)
• Loz: Fred Tatasciore (Agent Johnson from The Matrix: Path of Neo, Michael Eisner from Family Guy)
• Vincent Valentine: Steve Blum (Ares from God of War, Wolverine from Xmen Legends 2)
• Barett Wallace: Beau Billingslea (Mark and Jim from Resident Evil Outbreak, Cao Ren and Dian Wei from Dynasty Warriors)
• Cid Highwind: Chris Edgerly (many, many voices from Everquest 2, Lt. Col. Kanazawa from Project Snowblind)
• Yuffie Kisaragi: Christy Romano (Yuffie in Kingdom Hearts 1&2, Kim from Kimpossible)
• Cait Sith: Gregg Ellis (Disciple from Star Wars: KOTOR 2, Ty from Ty the Tasmanian Tiger)
• Red XIII: Liam O'Brien (Gaara of the Hidden Sand from Naruto, Dion Landers from Star Ocean: Til the End of Time)
• Reeve: Jamieson Price (Lu Bu from Dynasty Warriors, Wittcomb from Star Ocean: Til the End of Time)
• Tseng: Ryun Yu (Tenchu: Wrath of Heaven)
• Elena: Bettina Bush (Gloria from Madagascar)
• Marlene: Wallace Grace Rolek (Children’s Voices)
• Denzel: Benjamin Bryan (Odds-and-Ends characters from Without a Trace, CSI, Everybody Hates Chris and more)
• Zack: Rick Gomez (Gippal from FFX-2)
• Aerith Gainsborough: Mena Suvari (Aerith from Kingdom Hearts 2)
• Sephiroth: George Newbern (Nooj from FFX-2, Superman from Justice League animated series)