Mr. Bucket

The inlclusion of Mr. Bucket's character in Bleak House was the first police detective to be seen in Victorian fiction. However, the complex and multiple themes of Bleak House  does not constitute the novel as a detective novel. Detective novels came about later on when popular fiction was divided into genres during the late Victorian period. Some famous detective novels that came after Bleak House include The Moonstone (1868) and Study Scarlet (1887).

Source:

Banerjee, Jacqueline. Inspector Bucket Points the Way, 2013, www.victorianweb.org/authors/dickens/bleakhouse/bucket.html.