Origin

Haller first wore a battlesuit of an elephant. Later he would find a small shard of a gem of Cyttorak (notably not the Crimson Gem) that transformed him to a Man-Elephant. 

Creation

Manfred Haller was created by David Anthony Kraft, Mike Vosburg and Frank Springer in 1981and first appeared as Man-Elephant in The Savage She-Hulk # 17. Haller would transform into Behemoth in She-Hulk # 25 in 2005, written by Peter David and pencils by Adriana Melo. 

Mayor Story Arcs

Haller was a successful businessman that specialized in hydraulics and initially created the Man-Elephant battle-suit to save lives and enable explorers and construction workers to survive in hostile environments. Haller's plan to use the Man-Elephant suit to capture She-Hulk when she was wanted as a fugitive for publicity backfired when the emerald beauty defeated him. Haller would eventually go out of business by Tony Stark when he found out that he was supplying parts to unlicensed armored contractors. Haller traveled to Timbuktu where a blind, wise woman showed him a fragment of a gem that supposedly came from Ganesha, the God of Obstacles and New Beginnings. Haller touched the gem and was transformed into a new being, the powerful, humanoid elephant dubbed Behemoth. As Behemoth, he would save a family from some Tuareg rebels and then set his sights for revenge on Tony Stark and She-Hulk.  

Powers & Abilities

Behemoth possesses superhuman strength, durability and resistance to injury after obtaining the Seetorak gem which transformed him into a powerful, humanoid elephant. 
 
Prior to his transformation, Haller was a successful businessman with extensive knowledge and expertise in hydraulics. As Man-Elephant, Haller created a super suit modeled after the elephant. The hide was made out of rubberized material designed to withstand thousands pounds of pressure and resistant to powerful blows. The tusks could be used as a retractable grappling hook or to simply gouge, tear or gore. The trunk had the tensile strength far superior to steel and it could detect subtle odors. The trunk could also emit a sonic blast or knockout gas.