Debating about whether or not the original Die Hard is a Christmas movie only proves the point that it totally is. Yes, the man himself, Bruce Willis has (jokingly) said Die Hard is NOT a Christmas movie, but we all watch the 1988 classic around this time of year anyway.
The absolute banger of a first movie depicted NYPD detective John McClane (Willis) desperate to have a nice Christmas Eve, but instead, ended up having to fight terrorists in a high-rise building. From there, the Die Hard mythos was born...