This page contains information regarding Star Trek: Picard, and thus may contain spoilers.
Zhaban was a Romulan male who lived during the late 24th century. From the 2380s until his death in 2400, he worked as a housekeeper in the service of Jean-Luc Picard, alongside his wife Laris. He was a close confidant and advisor of Picard, and they held each other in high regard.
Zhaban and Laris were promised to each other at birth, in accordance with Romulan tradition. Zhaban's mother was a Tal Shiar operative who once revealed to Laris details of the rumored Zhat Vash organization. (PIC: "The Star Gazer", "Maps and Legends")
Laris indicated that Zhaban had also been a member of the Tal Shiar, and demonstrated combat training techniques when Château Picard was attacked by the Zhat Vash. He prepared to kill one unconscious, restrained attacker with an unarmed strike under the reasoning that they had no time and that others would be sent. However, Laris wanted to interrogate the man and reminded him that the pair "are not like them (the attackers) anymore." (PIC: "The End is the Beginning")
It was apparently through Zhaban that Picard negotiated his first interview with the Federation News Network since his retirement, having previously refused all requests. Zhaban reiterated three times that one of Picard's conditions for agreeing was that the interview would not address his resignation from Starfleet. However, during the live interview, Richter ignored this and did so anyway. (PIC: "Remembrance")
Some time shortly after the Zhat Vash attack on Château Picard, Zhaban passed away. Admiral Picard and Laris, Zhaban’s widow, reminisced about him while celebrating the end of the growing season in 2401. At that point, Zhaban had been dead roughly a year and a half. (PIC: "The Star Gazer")
Zhaban was played by Jamie McShane, in his second Star Trek role. The character was named by Alex Kurtzman in tribute to writer, executive producer, and first season showrunner of Star Trek: Picard, Michael Chabon. 
He is one of the few Romulans to sport a beard.
While Laris more closely resembles Romulans of the Original Series era, who are physically indistinguishable from Vulcans, Zhaban possesses prominent brow ridges like the Romulans which appeared during The Next Generation era series and movies. Laris calls Zhaban and a Zhat Vash agent with similar ridges a "Northerner." (PIC: "The End is the Beginning")
Before his first on-screen appearance, Zhaban was featured in the Star Trek: Picard - Countdown prequel comic book, alongside Laris. According to the comic, before the supernova, he and Laris were agents of the Tal Shiar who fell in love, and then defected to aid Picard. In issue #3, a Tal Shiar commander addresses him as "Agent Noctis".