Batiatus's mark.
The mark of Batiatus is given to all those of his slaves that have passed the gladiatorial test. It signifies their initiation into the brotherhood and their status as real gladiators, and not just slaves.
The Test[]
To be properly initiated into the gladiators, a slave must pass the test. This test takes place at the end of a recruit's training (which usually spans several days with little sleep). A wooden platform is erected in the training area of the ludus, and a recruit and a gladiator fight atop it. If a recruit turns out to be a bad fighter, he will be killed by his opponent. If a recruit proves he has talent, even if he does not win the fight, he receives the mark of Batiatus and becomes a gladiator.
Sacramentum Gladiatorum[]
"I commit my flesh, my mind, my will to the glory of this ludus and the commands of my master, Batiatus. I swear to be burned, chained, beaten or die by the sword for honor in the arena." - Recited by Spartacus in Sacramentum Gladiatorum.
The oath, sacramentum gladiatorum, is recited by every gladiator before the mark is applied to his arm. In it, he swears allegiance and his life to his Dominus, Batiatus. A glowing hot branding iron in the shape of a B is then pressed into his arms leaving a scarred 'B' in the skin. Until a slave receives this mark, he is considered merely a slave and is shunned and ridiculed by the true gladiators.
Ashur about to remove his brand.
Once part of the brotherhood, however, there is an unspoken pact between the members to protect and honor. This is shown by Crixus in Mark of the Brotherhood when he saves Spartacus from Segovax, ignoring his dislike for the man and saving a fellow brother. All those who are part of the brotherhood are expected to die a gladiator's death in the arena and nothing less.
Bearers of the Mark[]
Gnaeus displays the mark.