Wilhelm Casper was a German mercenary soldier who worked for Amalgam. His code-name with the group was Mr. Tin (Mr. Stannum).
A master sniper, he was Kurz Weber's mentor.
Casper was the latest in a long family line of snipers. He hailed from East Germany, and was described as being of Aryan decent. His grandfather supposedly served in World War 2, and earned a Knights Cross from killing many Alliance soldiers. His father was feared sniper in Indochina and Africa thereafter.
Wilhelm rose to prominence during the Russian Civil War, supposedly killing over 100 targets, as well as being active in Lebanon and Tajikistan conflicts.
His talents were regarded as being legendary, and in his own words he had the abilities of a "Ghost". This means having a natural, unconscious ability to visualise the shot, calculate all the variables and use a natural instinct to adjust to all of the physics and dynamics of a bullets travel.
Said to be able to shoot a hole in a coin from 1000m, Casper's talent was summarised by his record kill of a VIP target at 1520m, using an old 308 Caliber rifle with a 5 second target window. Kurz was his understudy and spotter during this shot, and explained it to some Mithril pilots;
"The record of Casper is 1520 meters. It’s short by 1000 meters from the ‘world record’. However, his weapon was a 308 caliber (7.6mm) wooden rifle. At night, raining, with the wind speed blowing 15 meters a second directly horizontal. And it was only one shot."
As a teenage mercenary, Kurz joined "Casper's Unit" in Lebanon and developed quickly as a sniper; though never to the equal of his teacher. Kurz sought revenge on a terrorist who was responsible for his family's death and when an opportunity to snipe him finally came, Kurz couldn't shoot him fearing collateral damage. Casper then took the shot, killing the target and severely maiming an innocent girl behind him without a second thought. Kurz was mortified by Casper's actions and lack of guilt, and left the squad.
Casper was later requested by Leonard Testarossa to be part of his bodyguard and strike team, specifically chosen to counter the select members of Mithril's SRT. He was provided an Erigor Arm Slave and first saw action against Kurz in Mexico, where he out-shot him and badly damaged his M9.
"You're good Kurz, but you still got a ways to go..."
Casper was also deployed to destroy the ARX-8 Laevatein in the West Sahara conflict, although Kurz had warned Sousuke Sagara about a possible sniper being involved after assessing the battlefield. This ultimately saved Sousuke's life when Casper finally took his shot, and it was able to be dodged. After return fire on his position from Mithil, Casper withdrew. Later, when Casper's Amalgam infantry team threatened to rebel against him, he shot the gentials of their leader from around 200m, instilling fear in the rest of the soldiers. Casper was also deployed to Yamsk-11 in Russia to counter Kurz's involvement and protect the Amalgam deployment. With both Arm Slaves hidden under the cover of ECS, Kurz was forced to guess Casper's location and took the first shot in an attempt to cover his colleagues. This revealed his position, and Casper successfully counter-sniped his M9, comprehensively destroying it with Kurz still inside, critically wounding him.
"Weber. How regrettable. You decided too early. You should have scrutinized it at least one more minute. I might have turned my head... How unfortunate, my student. But it was fun. I lent you a hand in your revenge. Instructing you in all of the arts. But, you can only go so far as to walk behind your teacher. Kurz Weber. You are such a blockhead. My student. How unfortunate."
After that exchange, Casper was goaded by Sousuke to leave his AS in order to shoot him with a conventional rifle. With Casper out of his AS, he was assassinated by shot through the heart from a dying Kurz, who had managed to crawl from the wreck of his AS with his wooden 308 calibre rifle received during his time in "Casper's Unit" and hit him with a "Ghost" shot from 1650m.
Capser's empty Erigor was then destroyed in the following battle between the ARX-8 and the Belial.