Among the three Bollywood actors - Shah Rukh Khan (SRK), Aamir Khan, and Salman Khan - who are all immensely popular nationwide in India, their popularity in South India can vary based on several factors including the type of movies they have acted in, their appeal to local audiences, and their overall box office success in the region.

Typically, Salman Khan tends to have a strong fan following across India, including in South India, due to his mass appeal and the success of his commercial entertainers which often resonate well with audiences across different regions.

Aamir Khan, known for his selective and often socially relevant films, also enjoys significant popularity in South India, especially among audiences who appreciate his versatile performances and the thought-provoking themes of his movies.

Shah Rukh Khan, while immensely popular throughout India and internationally, may have a slightly lesser presence in South India compared to Salman and Aamir Khan, primarily because his films often cater more to urban and Hindi-speaking audiences.

Overall, determining the absolute most popular Bollywood actor in South India among these three would depend on regional box office trends, audience preferences, and the reception of their films in that specific market.