Mafia

"The Mafia" is a west coast criminal organization allying with Mello which increases it's influence and intends to possess the Death Note and thereby gain power. How to Read 13 states that the organization is "being used by Mello."

Rod Ross
Rod Ross (Rodd Los in the Japanese version), real name Dwhite Gordon (Dwhite Godon in the Japanese version) is the head of the mafia. Ross follows Mello's orders. His name is easily known, so Light kills him.

Masaki Aizawa voiced Ross in the anime. Brian Dobson plays Rod Ross in the English Version. His name is also mentioned in L: Change the WorLd as the leader of an arms syndicate who deals with the mafia.

When asked by an interviewer who the most evil character in Death Note is, Ohba replied Ross, citing that Ross is "pretty darn evil" as he is the leader of the mafia.

Jack Neylon
Jack Neylon, whose real is name Kal Snydar (Kal Snyder in the Japanese version), is a member of Mello's crew. He is the holder and user of Sidoh's Death Note after it is given to them by the Kira Task Force. Before Mello joined, Jack was involved with drug trafficking and illegal weapons sales; neither of which charge stuck due to lack of evidence, despite four separate arrests. After Sidoh tracks down his Death Note, Jack performs the trade for the Shinigami Eyes. Light uses the Death Note to have Jack mail him the address of Mello's hideout. In the anime, the eye trade and first raid attempt were cut. He is voiced by Takashi Matsuyama in the Japanese anime and Ted Cole in English.

Other Mafia members

 * Zakk Irius (his real name) is used by the Mafia to converse with the Japanese police at the airport. The organization kills Irius after he guides Soichiro to the correct aircraft. He dies by heart attack when the airplane lands; his crew wrote his name into the Death Note.
 * Glen Humphreys & Rashual Bid are veteran gang members said to be the main force behind Ross. They are seen at the Mafia's hideout by satellite confirming its location, this behaviour was presumably manipulated with the Death Note by Light as an excuse for how he had discovered their true whereabouts (see Kal Snydar). They were killed by the Death Note during the raid by the Task Force members. Humphreys is known as Gurren Hangfreeze in the Japanese version and their real names are Ralph Bay & Al Meem respectively or Langford Bid & Yale Mison in Japanese.
 * Miller (real name Andrew Millar) is a member who was killed by "Y462" as a test subject as to whether the Death Note was real during the exchange. He was killed because he was stealing drugs from the gang to sell, and was described as an "incompetent guy".
 * Jose is not affected by the Death Note which kills the other members, as only his alias was known. He fakes being dead and fatally shoots Soichiro, then later dies when the rest of the Japanese Police enter the room and shoot him.
 * Roy & Skyer are not affected by the Death Note, which kills the other members. They attempt to retrieve the Death Note, but the task force disarms and subdues them both, yet they later (presumably) die when Mello detonates the explosives which destroy the entire building. It's believed that ownership was transferred to one of them after Snydar died only to be lost upon their own deaths.
 * "Y462" real name unknown, he makes the exchange with Soichiro for the Death Note and is the one to kill Miller. He holds ownership of the notebook for a short time but is killed by a remote explosive planted in his helicopter after he loads the Death Note onto the missle. His death causes ownership to be passed onto the Kal Snydar, the first one to touch the notebook after he dies. Ross had falsely promised that making the exchange would redeem him of his past failures.
 * ??? - Mello stated that he had several Mafia members use the Death Note before Ross did in order to learn whether or not the 13 Day Rule was false.
 * ??? - The pilot used by the Mafia to hijack the plane and drop of Soichiro at the exchange point though he might not be a Mafia member himself. His name was written in the Death Note by the Mafia after the exchange causing him to suffer a heart attack. He was stated to have been a veteran pilot with a clean record by Light.
 * ??? - After obtaining the Death Note Ross and Mello began killing their underlings and subordinates leaving only a chosen few.
 * ??? - Not knowing who were part of Ross' gang Light had the names of ALL known Mafia associates written into the Death Note most likely causing criminals unrelated to the kidnappers to die aswell.

In the Rewrite 2 special, the mafia are omitted, with Light's meetings with Kiyomi Takada and Teru Mikami moved to earlier on, and them instead being the ones to kill the SPK.