Prendick describes M'Ling as a "complex trophy of Moreau's skill, a bear, tainted with dog and ox, and one of the most elaborately made of all the creatures" (15.12). Unlike the other Beast Folk, M'ling lives in a kennel at the enclosure where he cooks and cleans and generally helps out around the house. He has glow-in-the-dark eyes and furry ears...
He's fiercely loyal to Montgomery, and this loyalty extends to protecting Montgomery, which he does twice in the novel. The first time, he chews out the throat of a fellow Beast Folk to protect his friend—seriously, he goes right for the jugular. The second time an untold party foul turns Montgomery's beach party into an oceanside brawl. M'Ling dies during the fight, more than likely still defending Montgomery.
M'Ling is easily the most elaborately characterized and complex of all the Beast Folk. His loyalty and love for Montgomery are distinctly human traits while his viciousness in combat feels animalistic. When paired with Montgomery, we see the difference between the Beast Folk and the humans shrink away.
See, M'Ling's "treat[s] Montgomery with a strange tenderness and devotion" and "whether [Montgomery] treat[s] it well or ill, it love[s] nothing so much as to be near him" (15.12). At no point in the story is M'ling's love for Montgomery ever in question. Meanwhile, Montgomery loves M'ling back, so long as he isn't drunk—in which case he becomes a right beast.
Quick food-for-thought question: M'ling is the only member of the Beast Folk given a name. Why do you suppose a name with such an Asian sound was chosen? What do you think this says about M'ling's place on the island as well as the novel as a whole?