OZ-00MS Tallgeese
The original mobile suit developed by the Organisation of the Zodiac, from which all other MSs were created. While being outdated, it possessed power and maneuverability so high it was quite literally a threat to its own pilot at times. Despite this possible danger and the suit's age, it was still taken to combat by Zechs Merquise, who felt its performance was necessary to challenge the Gundams. And the risks of piloting it as said above, it was also notorious for Zechs to suffer a heart attack when he piloted it for the first time despite him being a very healthy young man.