The Three Stooges are one of the most influential comedy groups in history, but their confusing membership calls for some clarification. The trio existed, in one form or another, for nearly 50 years. The need to keep earning money was partly influenced by the treacherous business practices of Columbia Pictures, who kept the performers on a fixed salary, keeping the massive profits from the shorts and never telling the Stooges just how popular they had become throughout their 24-year tenure at the studio.

https://screenrant.com/three-stooges-all-members-explained/