- You may be looking for Sutcliffe (The Juror's Story).
Lord Sutcliffe was a business man who utlised a sea serpent underneath the River Thames by feeding it humans attracted to the frost fairs who were eaten by the creature. It would later defecate faeces which could burn for longer and hotter than coal, even underwater which was greater than anything they had at the time of the Industrial Revolution. He kept the creature chained up underneath the Thames and as a result would cause the Thames to freeze over. Sutcliffe used this to lure people into the frost fairs which he'd feed the creature with to carry on producing his fuel. He also had two of his men convince con artists to lure others there and rob them to increase the size of the crowds further.
On 8 February, 1814, the first frost fair in years had arrived. As the frost fairs were becoming a rare occurrence, he planned to detonate an explosive which would crack the ice and feed everyone in it to the creature to carry on his fuel. However, the Twelfth Doctor and Bill learned of his endeavours, The Doctor outright assaulting him. However, the man had his henchmen capture the pair, where he proceeded to weakly justify his reasons for harming the creature, citing the deaths from mining coal and how he has advanced the British Empire only to be countered by the Doctor. Angered, Sutcliffe sent them to the lake where he planned to feed them to the creature as well. However, the pair escaped, Bill convincing the people to get off the ice while the Doctor rewired the explosives to free the creature. As a result, the ice cracked but only Sutcliffe was on it to fall in and drown.
Sutcliffe was a self-admitted sociopath; when the Doctor told him that the measure of a civilisation is how it values the life of an unimportant person, he responded that the speech would move anyone "with an ounce of compassion", then added that it wasn't the Doctor's lucky day. He was utterly ruthless and unscrupulous, seeing the people fed to the sea serpent and the creature itself as nothing more than pawns and fodder to be exploited in order to increase his wealth and power.
Sutcliffe was also profoundly racist, instantly accosting and undermining Bill Potts simply because of her skin colour and because she had set foot in his house, prompting the Twelfth Doctor to punch him in the face. What disgusted the Doctor the most about him, however, is that he was a normal human rather than an alien, saying that him being an alien would explain his complete lack of humanity. (TV: Thin Ice)