Kat McAllister in MobLand is a mysterious and extremely powerful figure in the criminal underworld, portrayed by Janet McTeer. She is depicted as an American crime boss with global influence, operating above the street-level conflicts between London crime families like the Harrigans and the Stevensons. Kat commands immense respect and control, able to influence even Mexican cartel bosses and halt violent actions with just a phone call

. Her role becomes pivotal when Harry Duza, the Harrigans' enforcer, calls on her to save Seraphina Herrian from execution by a cartel. Kat intervenes decisively, demonstrating her far-reaching power and strategic ruthlessness. However, her help comes with strings attached, as she makes it clear that Harry now owes her a favor, implying future complications and a deeper, possibly dangerous relationship between them

. Kat represents a shift in the show's power dynamics—from local gang wars to international crime networks and high-stakes power plays. She is wealthy, influential, and operates through intermediaries like Donnie, maintaining an elusive and commanding presence. Her arrival signals that the conflict in MobLand is escalating to a broader, more global scale, with Kat holding significant sway over the criminal world beyond London