To be more exact, it should be two "Marlowes" and one "Marlow".
The common thread among the common names is corruption. The playwright Christopher Marlowe authored the great English "Doctor Faustus." A few centuries later the Polish-born English novelist Joseph Conrad told at least two of his tales through a fictional character, the reflective seaman Marlow. And, some decades later, in the California, the paradise of the New World, one Raymond Chandler created a shabby, unbending private eye, Philip Marlowe.
I suppose that a quick Google search might reveal whether Conrad drew on the playwright, or Chandler on either. But I prefer to just start with the coincidence. (If Joyce had come up with the name, I would have thought, "Well, 'Mar' is the Aramaic title, "Lord." "Lord low"?)
Why corruption? I'll start with the playwright, and admit, at the start, that I don't really know his work, other than the "Faustus." But here we do treat of hubris, unbridled desire, the longing for lordship. Faust's insatiable desire for knowledge became, for Goethe, his (literally) saving grace. Not so with Marlowe's Faustus. Yes, I am uncomfortable with that last, desperate offer: "I'll burn my books!" But Faustus becomes his appetite, whether for knowledge, or women, or superiority, or even the simple pleasure of safe mockery. He authors his own damnation and fatally, he gets what he wants.
Cut is the branch that might have grown full straight,
And burned is Apollo’s laurel bough,
That sometime grew within this learned man.
From an author-Marlowe we move to an intermediate Marlow, Conrad's involved narrator of Heart of Darkness and more-detached narrator of Lord Jim. The two novels seem to have been written almost simultaneously. Kurtz is Conrad's Faustus, who finds only horror in the labyrinthine journey into, and out of, his own dark heart. By contrast, Jim, the young idealist, by great good fortune learns early of his own darkness, in a personal, and literal, fall from his charge, abandoning his passengers to what he fears and believes is an imminent plunge under a cold, dark sea. Marlow encounters Kurtz only at the brink of the frightful jaws of hell. Jim he meets at disgrace, in the facing of consequences, and in the fugitive run from remote outpost to remoter, seeking a personal redemption which Conrad, mercifully, allows him. Conrad's theme is corruption, but he does not insist on its inevitable victory.
And then there is our American Marlowe, Raymond Chandler's Philip, a character whose noir trappings and snappy patter all but obscure his genuinely heroic integrity. Chandler's novels are about corruption, the deep, unrelenting corruption of wealth, and he really makes us believe, as the apostle says, that the love of money is the root of all evil. There are gangsters, of course, and grifters, and cops on the take, but Chandler's real villains are the enormously wealthy men who appear only briefly, like Harlan Potter, in The Long Goodbye. His long tirade against human venality, population growth, publicity, the cost of war, "confiscatory" taxes, mass production, and the drug and cosmetics business, leaves Marlowe literally speechless: "I was sitting there with my mouth open, wondering what makes this guy tick. He hated everything."
That kind of power saps the spirit. "You've got a hundred million dollars and all it bought you is a pain in the neck." Every ordinary human desire is stifled. The rich (per the now-presumed-dead Terry Lennox) "never want anything very hard except maybe somebody else's wife, and that's a pretty pale desire compared with the way a plumber's wife wants new curtains for the living room." It is as much a hell as the playwright's "adders and serpents," or the seaman's "dark places of the earth" where bright intentions are put to the test.