The porcellanid species Raphidopus ciliatus Stimpson, 1858, and Raphidopus indicus Henderson, 1893, are reported from Singapore and Peninsular Malaysia respectively for the first time. This is the first record of the genus Raphidopus Stimpson, 1858, from Southeast Asia. A third species of Raphidopus, R. johnsoni sp. nov., is also described from Singapore mangroves. Pseudoporcellanella manoliensis Sankarankutty, 1961, a rare and unusual taxon, is also recorded from Peninsular Malaysia, the South China Sea and the Gulf of Thailand for the first time. Detailed redescriptions and extensive figures are provided for all four species, and their taxonomy and ecology discussed.