CBS is expanding the Blue Bloods universe with its Boston Blue spinoff - but who makes up the cast? Blue Bloods, which premiered in 2010, followed the lives of the Reagan family, many of whom worked for the NYPD under the leadership of NYC police commissioner Frank Reagan (Tom Selleck).

Earlier in the year, it was announced that the Blue Bloods universe would be expanding, and with the original series concluding last December, fans are ecstatic about what the next chapter will hold.