Optimus Primal is the leader of the Maximals in Beast Wars (1996). Despite the similar name, he isn't Optimus Prime but a different character from a different era.
Who he is
Primal is the captain of an exploration ship, not a warlord. His mission was meant to be peaceful until Megatron's Predacons stole an artifact and dragged both crews into battle on prehistoric Earth. His beast mode is a gorilla.
A leader who learns
Unlike Optimus Prime, Primal wasn't born a 'ready-made' leader. He doubts, makes mistakes and learns on the go, but always puts his crew above victory. In the series' best-known moment he risks everything to protect the sleeping Optimus Prime — in a sense, his forebear.
In the films
In Transformers: Rise of the Beasts (2023) Optimus Primal returns as leader of the Maximals hiding on Earth, voiced by Ron Perlman.
Why he's loved
Primal showed that a franchise hero could be not only a monumental commander but a curious, humane captain. Many fans consider him one of the best leaders in all of Transformers.
