The 51-year-old left his part as Paul Robinson on the Australian show in 1992 because he wanted to pursue new acting roles.
Reflecting on the decision, Dennis told TV Week: "I was stupid. I thought I was going to go to Hollywood and conquer the world, and I didn't. Fortunately, I worked constantly in the UK for the 12 years I was gone."
The actor also confirmed that he wants the soap's producers to retain Paul's "evil" streak in future plotlines.
He commented: "I hated [being good]. It was nothing like playing evil Paul. The fans like Paul to be bad too."
Dennis made a return to Ramsay Street in 2004, when Paul arrived back in Erinsborough with a bang by setting fire to Lassiter's.