|Full Name||Eustace Giuseppe Stern|
|Current Age||at least 10,000 years|
|First Appearance||Fantendo Smash Bros. X|
Eustace Giuseppe Stern, more widely known under the name "Deca", is a central character in the story of Fantendo Smash Bros. X. He is a seemingly immortal man, who holds a tournament once every 1000 years. He is seldom seen in person, primarily using his servant, a young boy named Harold MacArthur, as a proxy to relay messages to others.
Eustace Stern is a tall, thin man. As he has lived for over 10,000 years, he appears to be very elderly, being thin and very frail looking. He is primarily seen wearing a long, dark purple trench coat that reaches down to a pair of brown dress shoes, and a black fedora, though if the former is removed then his appearance is often compared to that of a skeleton. He has pale skin, and his bones protrude from his thin hands. His left arm and hand is mostly covered with bandages, and his left leg is a silver (though slightly damaged) prosthetic. He has heterochromia: his left eye is blue, while his right red; though he is also able to change their colour at will for a limited time.
When not wearing his fedora, Eustace has wild white hair not unlike the hairstyle worn by Albert Einstein in . He also has a large white beard that drops down to his thorax, as well as a small ruffled moustache that frames his top lip. Due to this, his appearance is often described as messy.
Very little is known about Eustace Stern, as he rarely makes public appearances. As the host of a tournament held once a millennium, he goes by the name of Deca, though speaks through a monitor and uses a voice modifier to mask his true voice. From this, it can be assumed that he has social anxiety, or is hiding away from society for a reason; allowing only his servant to speak to him in person. It is through MacArthur that he relays information, thus making it difficult to understand his personality as he primarily acts through a third party.
On the rare occasions where he does make physical appearances, he often speaks slowly, in a way that seems as if he is constantly thinking about which words to use and how to phrase them. It can be assumed that he is rather intelligent as well, considering his deliberate word choices and careful nature. He is also a rather calm fellow, very rarely raising his voice.
Despite his frail appearance, Eustace harbours immense powers, though prefers not to use them as they quickly wear out his elderly body. One of his many powers is the ability to change his eye colour for a limited time, which he often does to match his rarely-shown emotions. He has also demonstrated that he has superhuman strength and speed, though, due to his age, they are not as powerful as they once were. Eustace has also shown that he can create discs of water created by extracting it from his skin, though doing so enough will cause him to become dehydrated. He describes his own powers as a curse.
In his youth, he was stated to be a bodyguard for an unnamed royal, and as such is proficient in wielding a variety of weapons included maces, lances, claymores, and rapiers. It is hinted that he was alive during the Middle Ages, and that he was relatively well known during that era as a famed horseman.
Eustace Stern will appear as a central character in the story of Fantendo Smash Bros. X.
- Eustace (as well as MacArthur) was originally conceived to be an original playable character for Fantendo Smash Bros. X.
- Eustace claims that he is "more-than more-than-likely" the inspiration for the Dullahan, an Unseelie fairy from Irish myths.