Marv is a chubby, old human man with many wrinkles. He is mostly bald with patches of grey hair, bushy grey eyebrows, and bags under his eyes.
He is seen wearing a teal and white polka-dot button-down shirt, light brown business jacket, dress pants with a brown belt, and grey sneakers.
While little is known about Marv's personal life, it seems his career caused him many regrets. He is also a somewhat perverted man, who takes an inappropriate interest in many women he sees throughout the day; often having Princess Carolyn buy gifts for them, typically underwear.
He also seems to have been a sort of mentor to Princess Carolyn, telling her that sure, maybe one day she can be an agent—but right now she is learning from the best.
Marv makes his first appearance in a flashback, in the episode The Telescope.
After the success of Horsin' Around, and BoJack becoming a big celebrity, Marv calls his client to inform him that a Secretariat movie might be happening, and BoJack will most likely be playing the title role.
He also advises him, to not get into any trouble, and to "keep his head down and nose clean." He then hangs up, saying that he's got lunch with "MC Skat Kat."
Marv is seen shortly near the end of the episode, Still Broken.The BoJack Horseman Show, Marv calls Princess Carolyn, his secretary for fourteen years, into his office and asks for the scripts he read that weekend.
She first tells him, about No Country for Old Men and There Will Be Blood but he rejects and shreds both of the scripts because he finds the titles way too long. She then tells him about The Life and Loves of Mitch McFadden and his Friends and Family, a TV show script written by veteran sitcom writer Cuddlywhiskers.
Princess Carolyn shortens the title to "Mitch's Life." Marv loves the title and she then suggests that BoJack stars in it, but he laughs and refuses; saying BoJack turns down everything he gives him.
Princess Carolyn tries to defend BoJack, but Marv cuts her off and scoffs when she tells him she'd like to be an agent one day, saying one day she might, but for now, "she’s learning from one the greats."
Marv then states, that not even the best agent in the world could get BoJack to work, which gives Princess Carolyn an idea.
She goes to BoJack's house, with four Four Lokos. This gets him drunk, and he wakes up in her car.
Princess Carolyn tells him about the new show, and that she's taking him to meet with Cuddlywhiskers. BoJack rejects at first until Princess Carolyn promises if he does it, they'll have sex again later.At Cuddlywhiskers's house, Cuddlywhiskers tells BoJack the show idea came to him when he was in rehab, unlike his other shows, he wants to dig deeper. His latest show, Krill & Grace, didn't make him happy, neither did the awards or the money.Cuddlywhiskers then introduces BoJack to his assistant, Jill, and the two have something that lasts; and to send him an e-mail when he wants to stop being the horse from a "special relationship." He then continues to explain to BoJack that he's trying o do something different and stop being "The Horse from Horsin' Around."
The next day, Marv gets a call from BoJack, who has agreed to do the show.
Princess Carolyn goes to Marv and tells him that she finally wants to be an agent. Marv laughs at her at first, but then tells her, she can take his position and office—because he quits. He tells her that working there has ruined his life, and as a result, he has many regrets. However, after he leaves, Princess Carolyn still celebrates becoming an agent.
In The Kidney Stays in the Picture, Princess Carolyn has a flashback to when she was an assistant. Marv tells her he would love to give her a raise, however, he tells her she's thinking too much like an assistant. Marv tells her she's going to sign a new contract to become an agent any day now. She then asks if he really thinks she has what it takes to be an agent. Marv tells her sure but for now, he needs her to try on an apology bikini for an angry lady he fell on at the post office since they both have a similar build. He tells her to report back on where it pinches. Princess Carolyn takes the bikini and tells him she'll do it.