My first two "waves" of COBRA zombies were based on the special-infected ftome the Left 4 Dead games. Series three brings the freak-type zombies from another excellent zombie game, State of Decay.
State of Decay's Screamers lack any arms or lower jaw rendering them incapable of a direct attack, but their shrieking attracts hordes of nearby zombies and can disorient the living. Interestingly, a similar concept was planned by unused for the L4D special-infected.
Zombie-Viper - Head (cast)
Deadpool - Base figure
Namor - Feet