Steve Nallon (b. 1960) is a British impressionist, puppeteer, actor and writer who served as an additional performer on Muppet Treasure Island (uncredited) and The Dark Crystal: Age of Resistance. Nallon also performed the character of Cassandra (built by Jim Henson's Creature Shop) on What's Up Doc?
Nallon is best known for his impersonation of former Prime Minister Margaret Thatcher, which came to prominence on Spitting Image. Nallon was a leading impressionist on Spitting Image (also contributing impressions of Bruce Forsyth, Alan Bennett, Andrew Lloyd Webber, Roy Hattersley, David Attenborough, the Queen Mother, and many others) in addition to serving as a puppeteer on the program.