The books of the literary scholar and teacher PN Furbank, known to friends as Nick, who has died aged 94, reflected the wide-ranging interests of an inquiring mind, with biography as the principal strand. His best-known work was a frank and elegant account of the novelist EM Forster. The two met when Furbank was in his late 20s and had just been appointed fellow and director of studies in English at Emmanuel College, Cambridge. Forster lived in rooms in King's College and appreciated Furbank's command of languages when they went on holiday together.

By the 1960s, Forster realised that a biography of himself was inevitable: the notes to Wilfred Stone's study of his work The Cave and the Mountain (1966) had prompted interest by revealing the existence of the homosexual novel Maurice, started in 1912, which would be published only posthumously. Forster had initially asked the novelist William Plomer to write the biography. Plomer – whom Furbank described as "precise and sedate, with a teasing and foxy aplomb" – appeared a good choice but he soon became stuck, with a block against detailing Forster's sexuality. Forster's subsequent choice of Furbank was acknowledged by Plomer as inspired, and King's made him a fellow for work on it during the two years before Forster's death in 1970.

Publication of the biography in two volumes (1977, 1978) brought wide acclaim for Furbank, who was – as the critic and writer John Bayley said – "even more successfully and effortlessly en rapport with his subject than Quentin Bell in his biography of Virginia Woolf". Dealing with a range of matters from Forster's long ignorance of the mechanics of conception to his finding love on a tram in Alexandria, Furbank's pacey blend of comedy and pathos is worthy of his subject's novels. He also edited two volumes of Forster's letters (1983, 1985) with Mary Lago.

Furbank was born in Surrey, and his father was a bank manager. From Reigate grammar school, he went to Emmanuel College, where he gained a first in English, despite being profoundly upset by the death of his elder brother, an aspiring poet, in a flying accident in 1941. He then joined the Royal Electrical and Mechanical Engineers; as a corporal, he reached Italy in 1945.

The teaching post at Emmanuel came in 1947. A year later he produced a short book about the idiosyncratic Victorian writer Samuel Butler, now best known for The Way of All Flesh, defending him against an attack by Malcolm Muggeridge. In 1953, Furbank left academia, partly because of a stammer worsened by the prospect of lectures and tutorials. He became an editor at the publishers Macmillan, then a librarian at King's College London, and a freelance critic for the Listener. Alan Turing was a friend, and Furbank became his literary executor after the mathematician and computing pioneer killed himself in 1954.

Furbank's second book, Italo Svevo: The Man and the Writer (1966), showed his ability to depict with graceful economy the complexities faced by Aron Ettore Schmitz, an Italian businessman, who had written under the Svevo pseudonym but set aside his work until encouraged by James Joyce. The Irish writer had spent time in Trieste and met Svevo when he became his English tutor and then championed his book The Confessions of Zeno. Furbank was assisted by material given to him by Svevo's daughter. His incisive style combines wit and sympathy, depicting Svevo's wife, for example, as "mild, loving, literal, religious in a convent-educated way, responsive to Svevo's feelings and quite impervious to his ideas".

Forster's death upset Furbank more than he expected and the biography took some years to complete. During that period he also produced a short, wide-ranging study, Reflections on the Word "Image" (1970), exploring the ideas of image and metaphor. Surprisingly, he confessed in it that "if I talk to people on the train or … in the street, shyness can make me feel like a stranger hurled from a different planet, only barely able, by a huge effort of translation, to make my needs known to them". In 1972 he circumvented such problems by joining the staff of the Open University. This enabled him to teach at a distance and also undertake his many editing projects, including a series of Thomas Hardy novels. Pound (1985) is a witty introduction to a complex poet, written for Open University students.

In Unholy Pleasure: The Idea of Social Class (1985), Furbank addressed the shibboleths of a subject in which, for example, the term middle-class is so often reduced to such images as "polished doorknockers, perhaps, or windows with Staffordshire dogs in them and the Guardian on the doorstep". In analysing such matters as the journey of the word "bourgeois" from town dweller to one disparaged by Marx, Furbank pointed out that, fearful of parliamentary outcry, the Registrar General's Classification of Occupations (1970) omitted the upper classes. For Furbank, the ideal was to be a free spirit for whom the life of the mind is paramount regardless of position. He was a Forsterian humanist, treating each life on its own terms.

Astonishingly wide reading informs The Canonisation of Daniel Defoe (1988). Written with WR Owens, this described the way in which works were continually being attributed to Defoe, which meant that the canon grew, often misleadingly so. Far from dry, the book provides entertaining pen portraits of numerous obsessed scholars. Owens and Furbank's own Defoe studies led to A Political Biography of Daniel Defoe (2005), while their bibliographies whittled down the attributions, and they subsequently oversaw an elegant edition of 44 volumes, 10 of which Furbank himself prepared.

Meanwhile, Furbank had also been occupied with Diderot: A Critical Biography (1992). Previously he had deemed literary criticism to be no part of biography, but to his surprise, his treatment of Denis Diderot, a writer of fiction and plays as well as an Enlightenment encyclopedist, won the first Truman Capote prize for literary criticism. His political study Behalf (1999) examined the relationship between helping others and helping oneself.

A deeply reflective man, Furbank had a restless interest in the world. Only at the end of his life did he write about his fascination with cinema, completing a book, The Place of Film in the Arts. Also as yet unpublished is the anthology The Insect in Literature, on which he was working with Owens.

His marriage to the poet Patricia Beer ended in divorce.

• Philip Nicholas Furbank, literary scholar, born 23 May 1920; died 27 June 2014