Castlevania III offers up several different endings for you. The first of course is the original ending, with Trevor Belmont as the credits roll.
The second ending is if you played through with Grant. He will join you, and throw his hands up in triumph.
If you played with Sypha, it is revealed at the end that he was in fact a she. She and Trevor will share a hug.
If Alucard was your companion, he will join you, and your capes will both flap in the breeze. (I assumed there would be more to this ending, that there was, since Alucard is in fact the son of Dracula...oh well)