The Speaker is a humanoid individual of the MechanicalAge with elongated features. He serves the Black Ships as the right hand of the Ebony Cardinal and is seen with 3 other individuals of the same "race" next to the Cardinal's throne. It seems that he has the capacity of his majordomo and advisor, and also courtier and sycophant, and as his name suggests, he speaks in behalf of him.
He accepted the Arm who brought Sirrus and Achenar as captives and gave him leave. He then threatened the boys for daring to speak without having permission from the Cardinal.
After the Cardinal consecrated the bond of initiation and accepted them as his sons, the Speaker (or one of the others like him) guided them to a vault full of skull, as part of the third "mystery" of their initiation. He was also seen serving them, and asked Sirrus if the thrall who spilled his wine should be flayed alive.