Trader Derrick was a seafaring trader who often sold his wares on the Isle of Berk. However, one ill-fated voyage would prove to be his last.
Derrick looks like a typical generic Viking. However, he does have a particularly long, blond beard.
In the episode "Dire Straits", Trader Derrick, along with Trader Johann and several other merchants, was passing through the Straits of Baldur. Johann complimented him on his beard, before stating that he wouldn't be caught dead with a beard like that on his face. Suddenly, Johann, having smelled the gas bubbles of a Submaripper, alerted all of the other traders, including Derrick, who attempted to turn their ships out of the way. However, Derrick, along with every other trader except for Johann, was sucked into the Submaripper's whirlpool and killed. Johann, having managed to escape, later realized that he was all alone and expressed great shock and sadness at the deaths of Derrick and the others.
While Johann did disparage Derrick's beard, after having complemented him on it to his face, it is clear that Derrick and Johann were very close, as he is referred to as one of Johann's trading brothers and Johann is shocked and saddened by his death.