Marcus Nash is a real estate developer whose company competed with Ethan's.
Marcus was in competition with Ethan to develop real estate around LA. When Heather Reynolds hacked Ethan's company, Marcus used her to get and leak private information about Ethan's board of directors. In order to keep her quiet, he hired an assassin to kill her and make it look like a suicide. Alice investigated and figured out that this had happened and she and Ethan attended a party Marcus was having to announce his new acquisition, which he'd gotten by forcing Ethan out of the way. They printed off programs that listed what Marcus had done to Heather and displayed crime scene photos from Heather's apartment. He had them escorted out of the party, but the damage was done.
He had a professional rivalry with Ethan Ward.
He owns a real estate development company called Marcus Nash Properties.