C :

#include <stdio.h>

int main(void)
{
	printf("Hello World!");
	return 0;
} 

C++ :

#include <iostream>
using namespace std;
int main() 
{
  cout << "Hello World!";
  return 0;
}

Pascal :

begin
  writeln('Hello World!');
end.

Python :

# coding=utf-8
print("Hello World!")