He was a distinguished former editor of the Times Literary Supplement -- introducing unsigned reviews for the first time in that august publication -- and chief book reviewer on the New York Times for five years in the 1980s.
But he made lasting theatrical contributions with Shylock (1992), his brilliant tour around that difficult character in history and related literature, and with one of his celebrated anthologies, After Shakespeare (2002), which collected a rich bouquet of literary responses to our greatest poet from his own times to ours.
Gross often sat through first nights with an open text on his knee -- you felt that, like Clive James, he'd much rather read Hamlet than watch it -- but he was always the sprightliest and most stimulating company in the intervals.
And every theatre PR lady I know (including my wife) simply adored him; he was invariably witty and charming, with an attractive twinkle about him that no-one in the critical pack ever matched, then or now.
His first book, The Rise and Fall of the Man of Letters, will probably remain his most famous, though I suspect his modest memoir, A Double Thread (2001), will gain ground as a model of discreet, non-self-serving autobiography.
John's background was humble East End, born of Eastern European Jewish immigrants; he went down those same mean streets as Harold Pinter, who much admired his memoir, finding much he recognised.
He was a Fellow of King's College, Cambridge, in the early 1960s, but he often abandoned his students to their own researches while developing his literary career in London and working on his own projects.
Famously dubbed by the Spectator "the best read man in Britain," it would be hard to think of anyone since Samuel Johnson who seemed to have read everything, or at least know something about everything, in print.
Funnily enough, this didn't really come through in his theatre reviews, which were always interesting, often impatient with contemporary playwrights and "conceptual" productions, but sometimes a little flat. But there was never a false phrase, or an ill-chosen word, and everything was expressed with perfect taste and well-modulated tone.
The theatre critic post on the Sunday Telegraph has always been something of a part-time job -- when Irving Wardle stood in for Gross occasionally, the temperature, and the stakes, rose considerably.
But there have been some highly distinguished incumbents, and Gross was more than a worthy successor to Frank Marcus, Alan Brien and Francis King, all of whom were more immersed in theatre to start with than was he. And now? Let's just say he's much missed, on and off that newspaper.