These are Khon / Ramakien characters — Thailand’s masked classical-dance figures from the Thai version of the Ramayana epic.

In this post:
• Right figure (white mask): a monkey warrior, most commonly Hanuman (the famous white monkey general).

Center figure (dark/green-toned mask, royal crown, heavy armor): a yak (giant/demon) character — often shown as Thotsakan (Tosakan/Ravana) or another giant from the Ramakien.