Despite the fact that the free-body diagram is the most common method of representing forces in physics education, alternative means have been proposed over the years. Here we present a summary of the proposals found in the literature on physics education. We aim to discuss the pros and cons of these proposals, examine their degree of iconicity, and analyze their suitability for helping students understand the sum of forces (Newton's second law), the action-reaction principle (Newton's third law), and the nature of interaction (fundamental forces).