F42 may refer to:
F42 (classification), a disability sport classification F-42 (Michigan county highway) , a Niterói-class frigate of the Brazilian Navy , a Cunard ocean liner requisitioned for the Royal Navy , a Leander-class frigate of the Royal Navy , a Nilgiri-class frigate of the Indian Navy Obsessive-compulsive disorder Samsung Galaxy F42 5G, a smartphone