When Thor goes to Loki's prison to ask for his help, we see some creatures in the background who were brought in to captivity at the same time as Algrim/Kurse. These creatures are known as the Marauders. In the comic books, the Marauders are actually a group of mutant assassins who are employed by then X-Men villain Mister Sinister. However, because of the fact that Fox owns the movie rights to the X-Men and their villains, the Marauders are different in the Marvel Cinematic Universe and are portrayed as a group of relatively harmless rag-tag invaders of the nine realms. It seems like a very obscure inclusion in a Thor movie but it has indeed been confirmed to be true!