Wood Boy: Different death animations depending on cause
Squirrel Boy: Squirrels Will follow him
Needle Boy: Sends needles flying when moving. think

only the "rainbow" flies apart when it hits the ground due to its gravity
Blood Clot Boy: Sends out the amount of blood on impact that is equal to death splatter.
Salt Boy: Gets smaller the farther you go with him.
Missile Boy: has a missle smoke trail when jumping/ asplodes on death.
Brimstone Boy: singes ground/melds in to flame related deaths
Demon Boy: "flies" instead of jumps. screams and flies to start when defeated.
Maggot Boy: Drops harmless maggots constantly. Upin death in maggot pools he falls apart into maggots and then they join the swarm (no size change to pool)
Zombie Boy: does that brown explosion on death, if killed by zombie meat boys(or whatever they are) he runs to the spawn of that zombie as the player spawns
Dead Boy: INVINCIBLE!! but disables leaderboards and can't collect bandages or warp zones, and will die if he falls into things like maggot pools