From the Soulcalibur Wiki

A guest character is a playable character in a Soul series game who originates from another video game or other kind of media. To date, none has appeared in more than one game.

[edit] Soulcalibur II

Soulcalibur II was the first game in the Soul series to have guest characters, one unique to each of the home console versions. Link from The Legend of Zelda series appeared on the Nintendo Gamecube version, Heihachi Mishima from the Tekken series appeared on the Playstation 2 version, and Spawn from the Spawn comic book appeared on the Xbox version.

[edit] Soulcalibur Legends

Soulcalibur Legends had one guest character, Lloyd Irving, from the Namco RPG Tales of Symphonia.

[edit] Soulcalibur IV

Soulcalibur IV's guest characters are Yoda, Darth Vader, and the Apprentice, all from the Star Wars franchise while the Apprentice is specifically from the video game Star Wars: The Force Unleashed.

Darth Vader is available for play on the Playstation 3 version of SCIV, and as Downloadable Content on the Xbox 360 version. Likewise, Yoda is available on 360, and downloadable on the PS3.

[edit] Soulcalibur: Broken Destiny

Soulcalibur: Broken Destiny has one guest character, Kratos, from the God of War series.

[edit] Videos Exhibitions

Link, Heihachi and Spawn of Soulcalibur II 3 Versions Exhibitions	Lloyd Irving Gameplay in Soulcalibur Legends
Darth Vader Gameplay in Soulcalibur IV	Yoda Gameplay in Soulcalibur IV
Kratos Gameplay Trailer in Soulcalibur: Broken Destiny

[edit] External links

Info confirming Yoda and Vader's eventual meeting on the Stage of History

Guest character