|Played by||Seth Gabel|
Nikolai "Nick" Koslov is a murderer and a Russian mafia associate who appeared in The Big Picture. He is played by Seth Gabel.
Nikolai "Nick" Koslov is the illegimate son of Ivan Koslov, a leading member of the Russian mafia. His mother, Ivan's mistress, was an American prostitute who disappeared when Nick was a child. Though his father was a high-ranking gangster, Nick was never considered a true member of the family and wasn't let in on most of the mob's business in favor of his half-brothers. While having a legitimate job as a contractor, he also managed the family's prostitution business, overseeing the import of Russian girls to Los Angeles to serve as prostitutes. When Nick realized that he would be completely cut out of the organization when his father dies, he became a witness for the FBI in a RICO investigation of the Koslovs' drug business. While he was aiding them as a witness, he killed one of the prostitutes who worked for him, Vanya Kostenka, when she became pregnant with his child. He took Zoya Petrovna, another of his call girls, as his girlfriend. Six months after Kostenka's death, he killed Petrovna as well when she too became pregnant.
When Zoya's client list, which contained a lot of high profile names, was discovered, Priority Homicide was brought in to investigate her death. Looking through her house, Brenda tracks down Nick, who admits to having sex with Zoya but denies killing her. At the time of death, he claims, he was in custody at the FBI building. The FBI continuously provide Nick with an alibi, so Brenda calls him into Priority Homicide's office with the family lawyer present. When she reveals both Nick talking to them before and the fact that the FBI are backing him up, Nick confesses to murders in the hopes she will arrest and protect him, but she denies him such services. He is later found murdered with his throat slit.
Both of Nick's victims were Russian immigrants in their late teens who worked for him as prostitutes. After he got them pregnant, he would kill them by stabbing them in the back with a six-inch knife after having sex with them. The first time the blows are random but the second time he stabs her six times and the knife wounds are in the shape of a hexagon.
- An unspecified assault
- Vanya Kostenka (November 6, 2004)
- Zoya Petrovna (2005)
- Though Nick is first named as "Nikolai", Brenda calls him "Nicholas" for most of the episode.