|“||"So, you figured it out by now, right, Slick? Your body and name belongs to me now!"||„|
|~ Doopliss on stealing Mario's body and identity|
Doopliss is a major antagonist in Paper Mario: The Thousand-Year Door, appearing as the main antagonist of Chapter 4.
Doopliss is a Duplighost, a creature who is sheet ghost-like in appearance and has a special power which allows him to duplicate anyone he likes. This is special in the fact that when he does this he can steal not only their looks but also their name as well. The person he duplicates then become a shadowy figure of them self and cannot be identified by their friends, family, or enemies (well except for Doopliss himself). This was first evidenced when Mario and his partners beat Doopliss for the first time.
During their quest for The Ruby Star, Mario and his partners noticed the people of Twilight Town turning into pigs when the sound of a bell was heard. Mayor Dour told them that the sounds are a curse produced in Creepy Steeple and asked them to find out who is causing the curse. Once there, Doopliss revealed himself as the main cause of producing the sounds, this starts a battle between Mario and his partners and Doopliss. When Doopliss is beaten, Mario goes back to the new town he came from. Unknown to Mario's friends, this was not Mario but Doopliss disguised as him. The real Mario who looked like a shadow went back to the town but before he got there, he was ambushed by Doopliss Mario who told him that if he guessed his name that he would give Mario back his appearance and identity. If Mario guessed wrong he would face Doopliss in battle. Doopliss had an HP count of 40. Doopliss is into pranks as evidenced when Mario and friends got to the area he inhabited which was connected to a town which had an everlasting twilight over it. The area Doopliss was in was called Creepy Steeple. If you ended up battling Doopliss again, you had no other choice but to run away from the fight because now Mario's attacks were futile against him. When Mario got to the town he ran into one of the Shadow Sirens named Vivian who was looking for a Superbombomb. Once Mario found it for her she was thankful for him finding it for her that she joined him to get his identity back. Vivian had no idea who she was helping until the final time Mario faced Doopliss. When Mario guessed Doopliss's name wrong once again Mario still had no choice but to run away from the fight. When Mario and Vivian reached Creepy Steeple again they decided to find the person who knew Doopliss's real name. This "person" was actually a parrot. When Mario and Vivian reached Doopliss again, he asked them to guess his name. When inputting Doopliss, you must do it exactly like this: D-o-o-p-l-i-s-s, only without the little dashes. When Mario guessed Doopliss's name right he became upset and hid in the top tower of the Creepy Steeple yet again. This is where he was first fought. This battle, however, Doopliss was joined by Mario's friends except for Vivian. Doopliss's disguise managed to fool all of Mario's friends. However, Mario knew this guy was a fake. Once Doopliss was defeated he became regular Doopliss again and fled.
Doopliss was later spotted again on a train headed for yet another of the Crystal Stars. Here he disguised himself as a celebrity named Zip Toad who threatened to yummify the train if he went to Poshley Heights, the location of one of the Crystal Stars. He had become a member of the Shadow Sirens at this point. Mario caught Doopliss before he could carry out the threat and when he did Doopliss attempted to flee and succeeded when the train stopped to refuel.
Doopliss is found the third time in the Palace of Shadow, where he fought yet again, but this time, along with the Shadow Sirens, though Beldam rather calls him a Freak-in-a-sheet. After the battle, Mario once again defeats him and The Shadow Sirens, later he is seen along the Shadow Sirens rooting for the Shadow Queen.
After the Shadow Queen's defeat
After the Shadow Queen was defeated, he along with the Shadow Sirens fled from the Palace of Shadow. It was later revealed that Doopliss renounced to be a prankster and was hired by Flurrie to be an actor along with her, and now both are working in the stage where Doopliss plays Mario because he enjoys being him.