I have come across two lists recently on this subject. If you have visited my site, you will know that I am a glutton for lists. Two new lists relating to philosophy and the novel have recently appeared. The first is about whether it is still possible to write philosophical novels while the second is about top 10 philosophers’ novels. I have never heard of either author. Seán McGrady has a blog, which seems to be mainly verse, and published a book, of which I have never heard. Jennie Erdal has, apparently, been the ghostwriter of Naim Atallah, of Quartet Books and has written a memoir and, more recently, a “novel of philosophy” (i.e. it is about philosophers) which was presumably why she was asked to write this article.
According to his article, McGrady’s novel, his main character steals five pounds from his sister’s purse and then, I quote, His crime opens up a new way of looking at the world, and of acting in it, so his feet gradually find solidity in another mental milieu that better suits his questioning consciousness. I have no idea what that means but I cannot see how stealing five pounds would lead to all that. McGrady goes on to say that his character has religious doubt and is edging inescapably toward an ethical and ontological response; to resist a powerful milieu and affirm a new way. What I think that means is that his character is rejecting the culture of his background and looking for a new way of life, the theme of many novels that have never been called philosophical. 
McGrady does not define philosophers’ novels (novels about philosophers? novels read by philosophers? novels that have a philosophical basis?) but these “novels” range from Thus Spake Zarathustra to the Marquis de Sade’s favourite bit of porn to Iris Murdoch. I have read seven of the books he mentions, though, in a few cases, quite a long time ago. Thus Spake Zarathustra is not a novel by any stretch of the imagination. My review of Essays in Love by Alain de Botton, one of the first reviews I wrote for this site if I remember rightly, points out that the book is not really about love or philosophy but Alain de Botton and his sex life, not an engaging topic. I also commented that you will probably get more insight into love from Cosmopolitan. As for Il nome della rosa (The Name of the Rose), my review states that it is just a murder mystery. It is a very clever murder mystery and full of much learning, highly derivative, very intellectual, witty, superbly written, owing a lot to Eco’s interest in semiotics and an excellent introduction to medieval reasoning (seasoned with semiotic analysis). 
L’Etranger (UK: The Outsider; US: The Stranger) is famous for the acte gratuit of Meursault but also for showing the ennui, Weltschmerz and world-weariness of its main character and of us. In other words, it does have a philosophical basis, in that its main characters acts according to the existentialist philosophy of its author but, again, lots of 20th century novels do, including those by authors who have never heard of existentialism. In short, I am not entirely clear about what McGrady means by a philosophers’ novel.
Moving along to Jennie Erdal, we learn that she feels that philosophy and the novel are completely separate. The novel is about the the actuality of people’s lives (Harry Potter? The Twilight series? All of science fiction and other genre novels?), philosophy is not. However, she backtracks a bit, saying that there is something called the philosophical novel and that the fiction of Dostoevsky exemplifies what we have come to know as “the philosophical novel”. I am not sure if that is the case. Dostoevsky certainly deals with moral dilemmas. So does Harry Potter. Does that make them philosophical novels? She goes on to say that Iris Murdoch is still the author that people most frequently associate with the philosophical novel. Really? I associate Iris Murdoch with rather ponderous middlebrow novels that I read in my teens. Murdoch was a philosopher by profession, as well as a novelist, but that does not make her novels philosophers’ (or philosophical) novels. I think that there is a confusion here about novels that feature philosophers, novels written by philosophers and philosophical novels. But what is the philosophic novel? I have always held the view, doubtless expounded many times by others, that the serious, literary novel (and many less serious, less literary novels) are merely philosophy written in the form of fiction, as the human brain is much more able to comprehend a concept when given in examples, than it is able to understand the basic concept. Even supermarket trash fiction can deal with moral dilemmas, while many works of serious fiction deal with a variety of philosophical conundrums, without labouring under the stigma of being called philosophical novels. Or, to put it another way, most novels are philosophical novels. 
If McGrady’s and Erdal’s novels are self-consciously philosophical novels, I probably won’t read them but would encourage others do so. As for me, I shall carry on reading what I am reading, blissfully unaware as to whether they are or are not philosophical novels.