Julius Winkman was a shop owner and one of the most prominent illegal relic dealers. He bought stolen relics and auctioned them. His shop, Bloomsbury Antiques Emporium, acted as a front.
Pre-Lockwood & Co. Events Edit
Julius Winkman acquired the Bloomsbury Antiques Emporium from a previous owner who was accidentally crushed by an Indian erotic statue. 
Lockwood & Co. Events Edit
In search of the Bone Glass, Anthony Lockwood and Lucy Carlyle pretended to be casual civilians, visited Winkman's Store, and tried to survey the store's relics. They encountered the Winkmans - Julius, Adelaide the wife, and Leopold the son - for the first time. Their guises were uncovered when Julius Winkman saw the calluses, caused by holding a sword, on Lucy's hand - that they weren't civilians but agents. The agents left the store. Through his research and informants, Julius Winkman learnt the identity of the two youths.
Winkman finally held his auction at Rostock Fisheries warehouse. Among the attendants was Sir Rupert Gale who was yet unknown to Lockwood & Co. Lockwood and Lucy managed to infiltrate the auction, cause disorder, steal the Bone Glass, and escape.
At the same night, after the auction, when Lucy and Anthony rushed to the cemetery in search of the missing George, Julius Winkman had already sent his men to attack the youths. Lockwood & Co. with the help of Kipps's team defeated the assailants. After that night, investigations linked to Winkman and he was captured.
(Book 3) Anthony Lockwood, George Cubbins, and Lucy Carlyle had all testified against Winkman during his trial. Winkman was given about 20 years (the years were estimated) in Wandsworth Prison. The business was then taken over by the wife and son, and it was kept low.
A Winkman would again encounter Lockwood ad co. right before the parade of the agencies. Leopold Winkman crossed paths with Lucy and George and threatened Lucy about his father's early release.
(Book 4) When the Skull was missing, Lucy, who quit from her agency, hired Lockwood and Co. to help her reacquire it. The skull was stolen by Harold Mailer from Lucy's apartment. And then, he sold it to Adelaide Winkman. Adelaide held an auction that was again infiltrated by the agency. However, this time, Lockwood and Co. failed - they could not retrieve the Skull.
(Book 5) After 2 years (of about 10) of imprisonment, Julius Winkman was released for "good behavior". He was approached by Sir Rupert Gale to gather a group of men and attack Lockwood's home. Seeing a chance for revenge, Winkman complied.
At the siege of Lockwood's home, Winkman was heavily wounded when he fell on his own mercenary's drawn out knife. He died soon after. His spirit was seen floating away by Lockwood and co to some place else; which means that his soul is specially connected to something not to his body/bones. His Source was not mentioned at all. What would become of Adelaide and Leopold was not explored. But then the actions of Julius at Lockwood's home was clear to DEPRAC.
He was a small but muscular man. His height was a little higher than Lucy Carlyle's. He had a big head, thick neck, large shoulders, wide chest, and short and stubby feet. His and his family's physical descriptions were often described humorously by the narrator Lucy.