- “Heathcliff, my man!”
- ―Fred greeting Heathcliff[src]
Heathcliff's accent and characteristics suggests that he is of an English background. Following his graduation from butler school, he came into the service of San Fransokyo's Boss Awesome, as a right-hand man on various superhero missions. According to Mr. Frederickson, Heathcliff is the "best in the business" when it comes to undercover work, having disguised himself as anything from a doctor, to a hot air ballon enthusiast.
Heathcliff has since retired to serve as the head of the Frederickson household, as well as the family's chauffeur. He is undoubtably loyal to the Fredericksons, who treat Heathcliff as a member of the family. Due to the frequent absence of Mr. and Mrs. Frederickson, Heathcliff is often left to watch over and care for their only son, Fred.
Heathcliff is somewhat taciturn. He rarely emotes either physically or verbally, and simply carries out his orders without much personally input. In Big Hero 6, he was completely fine with Fred and his friends using him to test their powers-he even encouraged them and gave small smiles of congrats to Honey Lemon and Wasabi after their test runs.
However, Heathcliff is not as stiff as he lets on. He is something of a thrill-seeker, specifically finding enjoyment in busting criminals and high-speed driving. In "The Fate of the Roommates", he is revealed to be an activist for butlers who relishes in his chances to prove his worth to San Fransokyo's elite. Furthermore, he has a rarely-seen quirky side to his personality, as the episode "Kentucky Kaiju" revealed that he is quite fond of snow cones. Heathcliff also has a dry sense of humor, as seen when he taunted his racing competitor in "The Fate of the Roommates" by throwing back a disrespectful comment that the latter had made earlier.
Heathcliff is first introduced at Fred's manor, where he welcomes his master and the latter's classmates into the home. He is later seen assisting them in training for their battle against Yokai, albeit nonchalantly.
He isn't seen again for the remainder of the film, but Fred mentions him near the end, where he explains that the butler rescued them in the family chopper after being stranded on an abandoned island.
In the series pilot, "Baymax Returns", as Fred is in costume, monologging atop the manor in the rain, Heathcliff, standing on the ground with an umbrella, offers the young master hot cocoa, when Hiro runs up to ask for Fred's help. Later on, Heathcliff pilots the family chopper to extract Big Hero 6, including Baymax's rebuilt body, from Mr. Yama's lair. Some time later, Heathcliff becomes involved with Fred's desperate attempt to convince his friends to continue their superhero activities by showing off a superhero signal light, which was mistakenly misspelled "HALP" instead of "HELP"; Heathcliff sadly told Fred they didn't keep the receipt to have it returned.
In "Fred's Bro-Tillion", Heathcliff is filing Fred's toenail when the rest of Big Hero 6 burst into his room, having been summoned on an seemingly urgent matter. Heathcliff explained that Fred's bro-tillion, a grand gala held in his honor, was upon them, where he'd be formally presented to the city's wealthy elite, which Fred wasn't enthusiastic for. Later on, he informs Mrs. Frederickson that the caterer had canceled, even though he promised she'd pay extravagantly.
In "Muirahara Woods", Heathcliff drives the limousine to help Hiro, Baymax, and Fred tail Go Go to Muirahara Woods. While his passengers ventured into the woods, Heathcliff remains behind and relaxes in the hot tub.
In "Kentucky Kaiju", Heathcliff aids Fred in unboxing the Kentucky Kaiju figure used in the monster movies if the same name. Fred is disappointed by the revelation that the figure is the size of a toy, though Heathcliff doesn't see the problem and was instead hoping to unbox a snow cone machine. Fred soon got the idea to modify a crane, which he asked Heathcliff if he was technically the owner of, into a life-sized Kentucky Kaiju. Heathcliff later phoned the young master of the Kaiju's completion. This is followed up in "Fan Friction", in which Heathcliff scoops out all the koi fish out of a pond to enable Fred and Honey Lemon to practice combining their abilities, creating an ice sculpture that Heathcliff made snow cones out of.
In "Steamer's Revenge", Heathcliff gets an old-fashioned message from Baron Von Steamer requesting that it be sent to the Fredericksons. As Boss Awesome is out of town, it is decided that Fred will disguise himself as his father and be purposefully captured by Steamer to learn the villain's plans, allowing for Big Hero 6 to stop him. Frederickson video chats with Fred to teach him the ways of a superhero, with Heathcliff providing physical assistance.
- Having been present when the team was first formed, Heathcliff is actually the first character to have learned of Big Hero 6's true identities.
- He appears to be based on Edwin Jarvis, Tony Stark's butler from the original Avengers comics; and Alfred Pennyworth, Bruce Wayne's butler from DC's Batman series.
- When the team are testing their weapons on Heathcliff, he remains stone-faced and shows no concern for his well being, as if he had done this sort of thing before.
- When Heathcliff speaks in Big Hero 6: The Series, a piece of jingle music plays.