Landau, Luckman & Lake is an organization that provides specialized services to private clients. Wolverine has extensive history with LL&L who help in part to supervise his finances and private holdings, maintain his personal effects in long-term storage, and provide him with special orders and purchases, such as the body armor used by Psylocke during the Australian years. LL&L is actually an inter-dimensional agency pursuing its own agenda in addition to providing for its clients.
Gerald Lequare was originally the fourth "L" before breaking ties with his former partners.