Scalpel was a Decepticon Doctor. Of course, being a Decepticon, the term Doctor could easily double as Madman, Murderer, and a master in all forms of torture. Scalpel is all of this, despite being tiny even by Human standards. He, for some reason, enjoys taking rides to patients in the mouth of Decepticon Ravage.
When the Constructicons and Ravage arrived at the Marina Trench , they descended to find the body of Megatron. I hopes of him being able to save their leader, Ravage deployed Scalpel. Scalpel examined the damage and informed the Constructions that he needed parts, and to "Kill Ze little One". The Constructions then ripped the unfortunate Scrapmetal apart. Scalpel then used the AllSpark Shard to revive Megatron, who burst back out the sea.
Following the capture of Sam Witwicky, the Decepticons hoped to get the meanings of the symbols he was seeing out of him. Scalpel arrived to work on Witwicky, sending his assistant inside the Human. Scalpel probally would have begun worse, but Optimus Prime then arrived, and Sam swatted the tiny Decepticon off him. Some point in the fight, Prime shot Scalpel and blew him to pieces.