Derek Jupiter was born in London, England on 1970. He moved to the United States at the age of six. When Derek saw his dog's buttocks in 1984 it inspired the name of his hard rock band named "My Dog's Butt" while going to high school with his childhood friends Andrew "Burger" Pitt and Ashley "Ash" Tyler. The band started recording demos at Derek's room, which later became his makeshift studio. The band sent the demos to record labels, but none replied. The band changed its name to "Derek Jupiter and The Other Guys", a year later. Two months later, the two members asked Jupiter to change the band's name. He said no, three attempts later he agreed. Derek saw a weasel, which was crushed by iron which later inspired the band's name and "Iron Weasel" was born. In the mid-1990's, Derek dated his roadie Ernesto's girlfriend, Julie. When Iron Weasel split up in 2001, he had a solo career with the album "Derek". His album flopped and later lived with his ex-band mates in The Band Van a year later. Seven years later the band reunited, along with their new lead guitarist Tripp Campbell. Derek is now the lead singer of Iron Weasel.
- Derek is the lead singer of Iron Weasel.
- He is the tallest member of Iron Weasel.
- Derek is the only British member of Iron Weasel. He also speaks in a British accent.
- He formed the band.
- He dated Julie, Ernesto's girlfriend. Also as mentioned by him he dated many other girls.
- He has a guitar named Dereka.
- He sometimes can be selfish.
- Snakes are actually Derek's second fear as mentioned by him in "Spiders, Snakes and Clowns". His worst fear is cutting his hair.
- He can speak Spanish, Turkish, Japanese, and Swahili.
- Derek is an accomplished magician.
- He has a pure gold jacket.
- He is usually seen drinking water.
- Derek tends to bring up bad moments at many times, even though he does not like to.
- Derek is played by Steve Valentine.
- Interestingly, he is occasionally portrayed as being the second smartest, and is shown to have at least of a rudimentary understanding or knowledge of many advanced subjects like Greek mythology and English literature.
- He can play a guitar and a keyboard.
- He tends to storm out when he gets mad or when somebody lays too much pressure on him.
- Samuel accidentally used Voice Blaster to Space Godzilla voice into Derek voice. (different voice)
- He is seen as Tripp's father figure.
- He likes to play video games. Very much.
- He has been known to wear eyeliner.
- He tends to hold speeches even at most ridiculous times ("What Happened?"-He held it while Iris was giving birth) and when they fit in ("Lord of the Weasels")
- It's known that he can be cruel sometimes ("in "What Happened?" he made Burger hit himself with a vase so ambulance gan give the band a lift to the concert) and that he has a dungeon... for unknown reasons ("also in "What Happened?")
- He clams that being the leader is the core of his identity; he tends to get very upset when he thinks somebody tries to replace him as the leader of the band (as seen in "Lord of the Weasels").
- Also, his initials are DJ.
- Derek's singing voice is provided by Chuck Duran, lead singer of Rock Sugar.