From the Characters Page:
"Not -the- Oscar Wilde, just -an- Oscar Wilde. A writer from Chicagoland, Oscar rented Sylvia’s house from Barbara Yaga without knowing it was haunted. Oscar is good natured, even-tempered, and a little pedantic. He doesn’t like to talk about himself and finds ways to avoid conversations that get too personal. He has a weakness for beer and pretty girls."
Oscar Previously lived in Chicago, Illinois, presumably with his family. He has an older sister, River, and we know his Dad is still alive. Little is yet known about Oscar's mother, she may be alive or dead, and he seems to have a strong emotional response when events remind him of her. Oscar left Chicago for Podunk, Oklahoma when he was 25 years old, and there rented a house from Barbara Yaga after seeing her advertisement on craigslist. While not much has been said about why he did this, a journal entry of his shown on page 42 says "When I was 25 I ran from my demons and moved in with a ghost." It is hinted at elsewhere that he left because of some sort of problem(s) he was having in Chicago. The journal quote is phrased in such a way that suggests it was written when Oscar was older, but this could just be intended to make the journal entry more dramatic or eloquent.
Oscar has been seen to own or acquire several items, which have become somehow important to the story.
Oscar owns a dark gray (possibly black) Honda Accord. It is a 2008 model, as confirmed by the author in a Disqus comment. He drove it to Podunk and has since also used it to drive to and from the hospital with Becky and Cliff. It was also shown on page 143 that the car has a front vanity plate reading "T-800", a reference to the Terminator franchise.
After moving in with Sylvia, Oscar buys her several items to make her life as a ghost easier: a deck of cards, a polaroid instant camera with a large box of film, and a CD player/radio. He also went to the library and got her an audiobook, Slaughterhouse-Five by Kurt Vonnegut.
When Oscar first meets Clifford, he loans him a red sweatshirt. This jacket became the source of many jokes in the website comments and the author's social media, as Cliff kept it and wears it all the time.
These have been with Oscar from the beginning of the comic, and are part of his signature appearance. The glasses are black with rectangular frames. When Oscar first moves into the new house, Sylvia picks up his glasses to look at them. His glasses are also lifted off his face when Dani attacks him in the hospital.