葛兰姆 transliterates Graham, originally a Scottish surname. Notable bearers include American evangelist 比利·葛兰姆 (Billy Graham, 1918-2018) and various Britons named Graham. Note that 格雷厄姆 is a competing transliteration favored in some media.
usage
Sound mapping: 葛 for 'Gra-', 兰 for '-ha-', 姆 for '-m'. 姆 is a stock phonetic for the closing '-m' sound in English names.