The influential figures in Charles Darwin's life that shaped his theories include John Henslow, his mentor at Cambridge, and Thomas Malthus, whose ideas on population growth informed Darwin's theory of natural selection. Henslow encouraged Darwin's scientific interests, while Malthus' essays prompted Darwin to consider how organisms adapt and evolve based on their environment and resources. These influences were crucial in developing Darwin's groundbreaking theory presented in "On the Origin of Species."