Marrgu (Marrku) is an extinct[3] Aboriginal language of northern Australia.

Additional names include Ajokoot, Croker Island, Raffles Bay, Terrutong (Terutong), Yaako (Jaako, Yako).

[1] Marrgu had been assumed to be an Iwaidjan language like its neighbours.

However, Evans (2006) has produced evidence that it was a language isolate, with possible connection to the extinct and poorly attested Wurrugu.

[2] Marrgu has the three-vowel (/a/, /i/, /u/) system typical of Iwaidjan languages (Evans 1998).