What does ‘last but not the least’ mean?

‘Last but not the least’ is an expression which we often hear in public speeches.

For example, if there are many guests to be introduced on stage someone has to be mentioned last; last but not the least is used to show that the person mentioned last is equally important as the people mentioned before (him/her) or the last mentioned is not the last important just because he/she is last. The expression is also used in writing.

E.g. “Last but not the least, I would like to thank the audience for their patient hearing”.

According to a section of Engish scholars, this phrase was used in the theatre. It was common to use this phrase as part of the introduction of the characters on the stage.

It was also used by Shakespeare in ‘King Lear’:

Although the last, not least; to whose young love
The vines of France and milk of Burgundy
Strive to be interess'd;