Most commonly seen in 生肖 (shēngxiào, Chinese zodiac) and 肖像 (xiàoxiàng, portrait). As a surname, 肖 is a simplified variant of 萧 (Xiāo) — many people surnamed 萧 were reassigned to 肖 during simplification.
mistakes
As a surname it's pronounced Xiào (4th tone), but many people say Xiāo (1st tone) because of the connection to 萧. Both are heard in practice.