In life, Arragotus was supposed to be crowned prince, but he was murdered on the morning of his crowning. Angered by this, he seeks revenge and legend states that he will get his revenge if his rest is disturbed. This turned out to be true, as scientist Richard Klopfer discovered when he attempted to uncover Arragotus' tomb. After being brought back to life through the ancient words "ABASEEGO MODARO LAMADOROS CREBEN," which were written on his sarcophagus, he tore up Richard's face until his assistant, Bella Wortham, read the words again, putting him to rest.
Arragotus was then sent to Colin O'Conner's Haunted Horror Museum, where Colin's daughters Cathy and Shannon accidentally brought him back to life. After a struggle, Catchy was able to put him back to sleep by reading the words on his sarcophagus again. Soon after, Cathy's class came to the museum for an overnight and one kid accidentally brought Arragotus back to life after reading the words off a piece paper Colin had it on, along with various other papers. He was angry at Cathy for defeating him.
In a desperate plan, the kids brought Slappy the Dummy to life, hoping he could use his powers to stop him. Instead, Slappy only wanted to stop Arragotus so he could have the kids all to himself. Setting his sights on the dummy, Arragotus started to battle with the dummy, but every thing Slappy used to stop the mummy failed. Finally, Shannon managed to defeat him by tickling him.
However, when Cathy tried to read the words to put Slappy to rest, as he was still a threat, she accidentally read the words to bring Arragotus to life, meaning he likely came back to life soon after.
While not much detail is given about his appearance, he seems to look like a standard mummy, and it is stated that tar covers his eyes.
He is extremely angry and vengeful, as well as very strong. He does not take defeat well, as shown when he was angry at Cathy for defeating him. After being tickled to death, Colin O'Connor theorized that this stopped him because he just wanted a little affection after all these years.