How many die hard movies are there?

Live Free or Die Hard, released in 2007 and known outside North America as Die Hard 4.0, is identified as the fourth installment in the Die Hard film series. The film follows NYPD detective John McClane as he confronts a cyber‑terrorist threat. Because it is described explicitly as the fourth entry, the series must contain at least four films. No other Die Hard titles are mentioned in the provided evidence, so the count rests on the confirmed fourth installment.