A straphanger who witnessed the fatal subway confrontation between Daniel Penny and Jordan Neely earlier this month called Penny a “hero” for restraining the homeless man before his death.

The 66-year-old woman, who asked not to be identified, also said she’d testify on behalf of Penny, 24, who was charged last week with second-degree manslaughter over the deadly encounter.

The witness told The Post that Neely, 30, went on an explosive tirade just before his caught-on-camera death, telling people he was willing to “kill a motherf—-er” and “[take] a bullet” and go to jail.

Neely’s erratic behavior put commuters on the F train subway car on edge as they hurtled between stations in Manhattan, the witness said.... Read More: NY Post