some rare biggest and heaviest tanks of world war one era

American

Holt 200ton Trench Destroyer 1916 (200 tons)
(intended to be armed with six cannons, twenty machine guns and one flamethrower)

British

Tritton Foster Flying Elephant tank first version 1916

Tritton Foster Flying Elephant tank second version 1916 (the placement of the weapons remind of the A7V sturmpanzerwagen of 1917)
(and the first version and the second version were 100 tons)

Tritton Foster Battletank 1916 (100 tons)

French

 

FCM 1A 1916 (45 tons)

Russian

Mendeleyev Tank 1915 (170 tons)
(that is in the battlefield 1918 modification)

German

 

K Wagen 1918 (150 tons)

(that is in the battlefield 1918 modification)