利特尔·古斯塔夫

古斯塔夫 (Gustaf/Gustav) is a classical Swedish royal name — six Swedish kings have borne it, including the current monarch's namesake Gustaf VI Adolf. Pairing it with 利特尔 (Little) is a rare full-phrase transliteration, which suggests this is the nickname of a child character (storybook, comic, or game). The most native-sounding rendering would be 小古斯塔夫 (Xiǎo Gǔsītǎfū).

Two parts: 利特尔 = Little (Lì-tè-ěr ≈ Lit-tle), 古斯塔夫 = Gustaf (Gǔ-sī-tǎ-fū ≈ Gu-s-ta-f). The 夫 ending is standard for foreign names ending in '-f' or '-v' (高尔夫 golf, 巴甫洛夫 Pavlov).