From Destinypedia, the Destiny wiki
Fallen Commodores are extremely large variants of Brigs employed by the House of Salvation. They stand more than twice as tall as regular brigs similar to the size of Insurrection Prime and have more durable armor.
Apart from design and appearance, they have the same gameplay as regular Brigs apart from some of their attacks being intensified such as their Ground stomp/slam attack. They also have the unique ability to sustain large Stasis shield domes as seen in Stealing Stasis.
List of appearances