Because Sinclair had to be written out of the show, his role as the CO of Babylon 5 was given to the newly created John Sheridan. While their differing personalities impacted some plotlines ...

In the Babylon 5 series finale, a dying John Sheridan is greeted by Lorien, who leads him to beyond the Rim. Sheridan is never seen again, although it's left ambiguous what exactly happened to him ...