A giant in the fight to secure health care funding for first responders battling 9/11-related illnesses has died.

Ray Pfeifer passed away on Sunday after battling cancer for several years at 59.

The 27-year FDNY veteran from Hicksville spent eight months working on the pile at Ground Zero in the aftermath of 9/11.

In recent years, Pfeifer joined with other 9/11 first responders in successfully lobbying Congress to pass and then renew the Zadroga 9/11 Health & Compensation Act.

Pfeifer also received keys to New York City and Nassau County for his work.