Call of Duty: Black Ops

This is really easy, but just to make sure people don't miss it I’ll spell it out. *Almost slight spoiler*

You get a slowmo scene here when you find Castro in his bed room with a lady friend. He'll use her as a shield, but even on Veteran the slowmo makes it easy enough to get the head shot on your first try. You'll know you did it right when you get a "bullet cam" that follows the bullet right into Castros head. *BOOM! Headshot!*

Edit: Hey thanks to LionSquirrel02 it's confirmed that you need to get it on the first shot. So when the slo-mo starts make sure to go strait for the head and don't dilly dally. Awesome work LionSquirrel02!

As shown in the video below, start the first mission. About halfway through you look from room to room to find "Castro". You won't find him in the first slo-mo breach you do, but the second one you find him with a girl. He uses the girl as a shield so just take your time and aim straight for his head. You should see a slow shot of the bullet hit his head and when he dies you will get the achievement.

Spiderbite from NextGenTactics walks through and tells you how and where to get this achievement. It is kind-of hard to miss but just in case you missed it go back and get it.

Mission: "Operation 40"

Quite simple really. When you enter Castro's room you'll find him stood in front of his bed with a lady friend as an hostage. Don't touch the analogue stick and you will find his head is already perfectly lined up, just pull the trigger and BOOM! Headshot city!

This achievement is done opn the mission operation 40 (the frst mission of the game) unfortunately you will need to get quite a ways throught the mission before you have a chance to do this. Make sure you are well hydrated and well rested before attempting this. It requires a steady hand and a certain amount of concentration. Obviously this is easiest on recruit, so either start a new game on recruit or just mission select.

Play through the mission as you normally would, nothing special here. Move and shoot, nothing special. You will eventually come to an area of the mission that reqires you to breach a door. Your partner, Frank Woods, will open the door for you and you will need to take out the few enemies inside. After this is done, follow woods a few feet to the right to another door. Your character will automatically pull out a pistol, the ASP, and Woods will breach the door. Time will slow down as you enter the room, now is the moment of truth.

Fidel Castro (a Cuban politician and revolutionary who governed the Republic of Cuba as its Prime Minister from 1959 to 1976 and then its President from 1976 to 2008. Politically a Marxist–Leninist and Cuban nationalist, he also served as the First Secretary of the Communist Party of Cuba from 1961 until 2011. Under his administration Cuba became a one-party communist state; industry and business were nationalized, and state socialist reforms were implemented throughout society. Internationally, Castro was the Secretary-General of the Non-Aligned Movement from 1979 to 1983 and from 2006 to 2008 - Wikipedia), the male in the room wearing greeen will grab the female and use her as a human sheild, obstructing most of his body. However his head is still open. You have a few seconds to act and must be relatively precise with your shot. Aim for anywhere on his head (eyes, nose mouth, etc) and as long as you aim here and pull the trigger (you only need to pull it once).

You will know if aimed properly because you will get a neat bullet time kind of animation whioch follows the bullet as it travels in slow motion. Boom! headshot, Castro dies, achievement pop! be aware however the female he used as a human sheild will quickly grab the rifle on the bed behind her, so take her out immediately after.