Data

Lieutenant Commander Data was a Soong-type Android, the first and only such being to ever enter Starfleet.  Data was created around 2330 and was destroyed in 2379 because he sacrificed himself so that the crew of the USS Enterprise could survive.  One of Data’s most famous quotes was “I chose to believe that I was a person, that I had the potential to become more than a collection of circuits and sub-processors.” 

Data was a machine but he aspired to be more human.  He had some failing results.  Data tried to use humour and romance which sometimes worked.  Romance never seemed to work out for Data.  He mostly had problems using contractions in speech.  Data was the fifth of six complex Androids known to have been built.  

Data was a Starfleet Officer for many years before he became the Operations and Second Officer of the Enterprise.  Data often took the night shift as he did not need sleep and could work 24-7 without rest.  Data was recognized as a machine and some people did not think he should have rights as a human.  Some people only felt he was  property to the Federation almost like a slave.  But all those who had such thoughts were proven wrong when they wanted to take Data apart for scientific reasons as it was determined that he was his own life form and a race within himself.  

Data died in 2370 to save the Enterprise from a deadly weapon that would have destroyed the whole Enterprise.  Before he died, he transferred all of his memories to a test model Android which was not as advanced as him and could not communicate as well as he could because he could not create full sentences.  It was suggested Data was reincarnated in the test model Android’s body by using Data’s memories but the test model Android was not Data as Data was unique.