Will Ferrell

Sherlock Holmes

John C. Reilly

Dr. John Watson

Rebecca Hall

Dr. Grace Hart

Kelly Macdonald

Mrs. Martha Hudson

Rob Brydon

Inspector Lestrade

Lauren Lapkus

Millie

Pam Ferris

Queen Victoria

Ralph Fiennes

Prof. James Moriarty / Jacob Musgrave

Adam Scherr

Brawn

Kieran O'Brien

PC Smalls

Noah Jupe

Doxy

Bella Ramsey

Flotsam

Scarlet Grace

Pickle

Billy Jenkins

Mud Fog

Michael Culkin

The Judge

Wolf Roth

Sigmund Freud

Jana Pérez

Lestrade's Wife

Nathan Osgood

Mark Twain

David Shackleton

Albert Einstein

Bronson Webb

Jonathan Nightingale

Jason Thorpe

Butler

Oliver Maltman

Telegraph Operator

David Stoller

Hudson's Guard

Lilly Aspell

Newschild

Ethan Rouse

Newschild

Helen Duff

Titanic Guest

Jess Liaudin

Hangman

Daniel Fearn

Drooling Man Companion

Martin Bishop

Priest

Gerard Monaco

Titanic Ship Officer

Ben Lee

Houdini

Michael Buffer

Fight Fan #1

Bruce Buffer

Fight Fan #2

Russell Wilcox

Announcer

Billy Zane

Billy Zane

Codie-Lei Eastick

Young Watson

Sadie Newman

Jane

Ella Bright

Bridgette

Kenneth Hadley

Headmaster

Paul Bigley

Teacher #1

Sue Maund

Teacher #2

Paddy Holland

Tough Kid

Deepak Anand

Nobleman (uncredited)

Martin Bassindale

One Man Band (uncredited)

Steve Coogan

Gustav (uncredited)

Shawn Dixon

Upper Class Gentleman #1 (uncredited)

James Eeles

Manager Mr. Petrucka (uncredited)

Hugh Laurie

Mycroft Holmes (uncredited)

Jordan Long

Herbert (uncredited)

Jorge Leon Martinez

British Soldier (uncredited)

Martyn Mayger

Buckingham Palace Guest (uncredited)

Steve Coogan

Gustav Klinger (uncredited)