Malcolm Dresden is Harry's father. He gets the following introduction in Storm Front:
He was a good man, a generous man, a hopeless loser. A stage magician at a time when technology was producing more magic than magic, he had never had much to give his family. He was on the road most of the time, playing run-down houses, trying to scratch out a living for my mother. He wasn't there when I was born.
He wasn't there when she died.
He showed up more than a day after I'd been born. He gave me the names of three magicians, then took me with him, on the road, entertaining children and retirees, performing in school gymnasiums and grocery stores. He was always generous, kind-more kind and more generous than we could afford, really. And he was always a little bit sad. He would show me pictures of my mother, and talk about her, every night. It got to where I almost felt that I knew her, myself.
As I got older, the feeling increased. I saw my father, I think, as she must have-as a dear, sweet, gentle man. A little naive, but honest and kind. Someone who cared for others, and who didn't value material gain over all else. I can see why she would have loved him.
I never got to be old enough to be his assistant, as he had promised me. He died in his sleep one night. An aneurysm, the doctors said. I found him, cold, smiling. Maybe he'd been dreaming of Mother when he went. And as I looked at him, I suddenly felt, for the very first time in my life, utterly, entirely alone. That something was gone that would never return, that a little hole had been hollowed out inside of me that wasn't ever going to be filled again.
In Fool Moon, the demon Chauncy hints that Malcom's death was unnatural, but his killer's identity has not yet been established. It is also not established how much he knew of the supernatural community and his wife Margaret LeFay's past.
When confronted with the apparently conflicting timelines of Harry and David Copperfield, Jim Butcher stated on his forum:
Harry's dad was acquainted with David Copperfield from the Society of American Magicians when both were at a similar point in their careers—just getting going. Malcolm was a bit older and more experienced, but didn't have the same kind of raw talent and had not had any major success or anything. Malcolm had an enormous amount of admiration for the young performer (and may or may not have contributed the notion for his stage name)."
On the TV Show
On the TV show, his name is shortened to Colm Dresden. He is still a stage magician, but his skills in that field are not very consistently represented. In several episodes, he is shown to be a rather poor performer, yet in "Storm Front" Harry claims he once opened for Sinatra. He is well aware of the magical community and determined to keep Harry separated from it, a point neither confirmed nor denied by the book series. He dies of a heart attack when Harry is 10, as opposed to his death by brain aneurysm when Harry is 6. His death is very clearly stated to be Justin Morningway's handiwork. In the book series, it is hinted that Malcolm's death is unnatural, but the killer's identity has never been explicitly revealed. Colm is played by Jonathan Higgins.