|First appearance||S2E01: Fugitivus|
|Last appearance||S2E07: Sacramentum|
|Relationships|| Glaber (Friend, deceased)|
Mercato (Friend, deceased)
Seppius (Friend, deceased)
Seppia (Friend, deceased)
Publius Varinius (Friend, deceased)
Albinius (Friend, deceased)
|Status||Unknown (presumed active)|
Magistrate Gallienus is middle-aged nobleman of average height and short black hair and is more rotund than most of his fellow Romans. Like all high-class politicians, Gallienus is dressed in fine clothing, specifically magistrate robes in red and white colors.
Described as "sour Gallienus" by Glaber, he is constantly distressed, cautiously apprehensive, and restlessly uneasy, Gallienus maintains authority of Capua over an era of political and cultural disorder. Coming off as somewhat frantic about his unfortunate situation, Gallienus does his part to ensure the city remains calm, cool, and collected as Spartacus and his rebellion threatens to shake Rome at its core. However, like almost all Romans of considerable power, Gallienus also enjoys a lifestyle of fortunes and riches.
Because of his stressful occupation, Gallienus is easily irritable when questioned over annoyances, and prefers not to be bothered over trivial matters. When not disrupted by the events of his day, Gallienus basks in the delights of Roman society. He has a friendship with Mercato, who is also tasked with pleasing the people, and gets along with other Romans very well.
Despite, to some extent, having a comedic overtone, Gallienus also manifests a sadistic and twisted side to him, represented by his ruthless cruelty towards Acer's torturous death, and his joyful laughter upon Acer's pain.
After Titus Calavius' death, Gallienus takes over the responsibilities of a magistrate, and assumes the position. He is first seen attending games in the pulvinus with Seppia, Seppius, and Mercato, where he laments the poor showing of the gladiatoral battle. He is then shocked at Seppia's news of Seppius losing eight men to Spartacus, and, despite the surrendering gladiator giving the missio, the magistrate orders his execution out of frustration.
Before the games of Publius Varinius, Gallienus participates in the torturous death of Acer, laughing maniacally as he slashes Acer across the side of his waist. He then watches the games from the pulvinus alongside other prominent nobles, such as Glaber and Albinius, where he witnesses the planned execution of Crixus, Oenomaus, and Rhaskos. However, Spartacus interferes on their behalf (despite Rhaskos falling), and soon the arena collapses by the efforts of the rebels. Gallienus and the other high-ranking Romans are shaken by the rumblings of the arena and try to clear the ruined pathway to escape the pulvinus, but not before Mercato and Cossutius are killed in the hysteria. The magistrate and the others manage to escape. As the Arena burns down behind him, Gallienus tries to calm frantic citizens from the outside as they too try survive the carnage.Gallienus then mourns the loss of Mercato with Seppia, and speaks with Glaber about the future restoration of Capua. The magistrate is last seen in the town square, where Gannicus approaches him and expresses his desire to be compensated for the games. Gallienus is at first unmoved by the gesture,considering Gannicus to have failed in properly executing the condemned. After some coaxing he gives in and hands Gannicus some denarii as a reward for pleasing the crowd for many years. The visibly annoyed nobleman then tells Gannicus to stay out of his sight, but is further irritated by former champion's questioning of his missing rudis. Glaber then announces execution of slaves who speak of Spartacus, from which afterwards Gallienus isn't seen again, presumably fulfilling the roles of a magistrate in the wake of chaos.
- Magistrate Gallienus remains the sole survivor of the ten nobles who attended the games of Publius Varinius from the pulvinus; the other nine ( Gaius Claudius Glaber, Ilithyia, Lucretia, Seppius, Seppia, Albinius, Cossutius, Mercato, and Varinius) are all dead.
- As a local politician, Gallienus would be part of the regional Roman governing elite known as the Curiales or Decuriones, who were landowners and merchants, who governed the lower level municipalities of the Roman Republic.
- It is implied in the series that Gallienus is a governing magistrate in Capua, which could mean that holds the office of Duumvir, or one half of the Duumviri (rule by two men) who were the town mayors of Roman society.
- Gallienus may be related to, or a member of, the Gens Egnatia, a Roman clan of Samnite descent, with various branches in Campania, Etruria and Rome itself. A future Roman Emperor Gallienus (reigned 253-68 CE) was descended from both the gens Egnatia and the Licinii.
- Gallienus: "The crowd demands spectacle, Mercato."
- On gladiator fight: "A poor showing."
- To Ilithyia: "A thoughtful offer. There is no deeper solace for a woman than in the bosom of her gender."
- To Gannicus: "Now, follow once noble monument and collapse from sight."