The Mad Artist is the Villain from the Haunting Hour episode "Brush with Madness"
The Mad Artist is an arch villain that Corey had created when he was painting comic book panels on his wall. Corey was shocked when he realizes that The Mad Artist resembles to a famous artist Allan Miller.
The Mad Artist was seen a second time in a black vehicle going after Emma, as he was about to exit out of his vehicle he got back in and drove off when Corey came to Emma's rescue.
Later on as The Mad Artist was following Emma he finally captured her knowing that Corey would be on his way to rescue her again. Once The Mad Artist captured both Corey and Emma he explains to Corey that he was the one who had created him (not Corey creating The Mad Artist). We last saw The Mad Artist pulling down a machine saw and pushing it towards Corey and Emma as the scene was transforming back into a comic book panel, meaning that he was going to cut Emma and Corey both in half.