Could see Samurai as a tank that focuses heavily on the block/dodge/parry mechanics, with counter attacks and life steal thrown in as well.

Defender/Sentinel, just two big shields, possibly with blades on the edges, doin shield stuff. focuses on disrupting the enemies attacks, reflecting damage back at them.

Magus as a magical tank? Charm as a magical enmity spell, can cast shell, barrier, etc. spells to heal themselves and remove status effects, etc