Tristram Shandy, whose autobiography the novel purports to be, is the hapless son of an English country squire. From his conception onward Tristram is the victim of a series of minor accidents, which he does his best to recount with good humor and mild self-mockery. Tristram's conception, birth, and baptism are the ostensible subjects of Vol. 1–4, though the novel ends up being pretty light on autobiographical details. Later in life Tristram contracts tuberculosis, which was at the time a generally fatal illness. He spends Vol. 7 on a trip through France in an attempt to cheat death—and, more practically, recover his health via a change of climate.
Walter Shandy is the patriarch of the Shandy family and the father of the protagonist. Having worked as a merchant in Turkey, he retires to his countryside estate, Shandy Hall. There, he spends much of his time attempting to raise his two sons according to his own detailed theories of childhood education. He is foiled at every turn: Bobby, the elder son, dies suddenly, and his younger son, Tristram, proves to be accident-prone and physically frail. Walter has peculiar opinions on a wide variety of subjects, reinforced by his extensive reading of philosophical and scientific writings. His typical approach to a problem is to go to his library and dredge up all the information he can find on the subject, even if decisive action is called for. Tristram tends to regard his father as a harmless, well-meaning eccentric.
Captain Toby Shandy, alias Uncle Toby, is a retired army captain who fought in the Nine Years' War. He was discharged from service after receiving serious injuries at the Siege of Namur. Once he has recovered sufficiently to walk about, Toby moves to Shandy Hall, where he spends most of his time researching and building model fortifications. A pair of extended flashbacks further develops Toby's character. In Vol. 6 he is shown tending to a dying soldier and later caring for his orphaned son. Vols. 8 and 9 focus on Toby's ill-fated love affair with the Widow Wadman, an episode that reveals his total inexperience in romantic matters.
Parson Yorick is something of an anomaly: a village priest who loves jokes and pranks, shunning the excessive seriousness of his fellow clerics. He is humble and genuinely concerned for his flock, though he suffers from the same pedantic tendencies as most of the men in the novel. Like Tristram, Yorick has many traits which seem borrowed directly from Sterne's own life, such as a keen and sometimes controversial sense of humor. His sermon on conscience at the end of Vol. 2 is, in fact, one that Sterne composed for his own congregation.
Corporal Trim (his real name, James Butler, is seldom used) once fought overseas under Uncle Toby's command. Like Toby, he has had his military career cut short by an injury, but he remains a soldier and a patriot at heart. After his retirement from the army, he serves Toby as a valet and relocates with him to Shandy Hall. Most of the servants at Shandy Hall are minor characters who function simply to advance the plot and provide a laugh here and there. Trim is the exception: appearing in almost every volume of the novel, he emerges as a well-rounded character who is notable for his loyalty, thoughtfulness, and unpretentious ways.
Mrs. Shandy appears much less frequently in the novel than her husband and his brother. She is portrayed in an affectionate but rather unflattering light and is often the butt of jokes. Her relationship with Walter is a quarrelsome one: although she is sometimes willing to placate her husband's odd whims, she stands up for herself at other times, as when she insists on choosing the midwife who will deliver Tristram.
Of the major recurring characters in Tristram Shandy, Dr. Slop is the closest to an unflattering caricature. Walter pays him to be on call during Tristram's birth and to take over when the other midwife fails to complete the job. In the process of delivering Tristram, he accidentally smashes the boy's nose flat with a pair of medical forceps. As a doctor, Slop is incompetent if not outright harmful. Physically, he is described as a "little, squat, uncourtly" fellow; the name Slop gives him a further air of piggishness. Fond of coarse jokes, the doctor fits uneasily into the Shandy family circle.