Wally

Wally is a friend (and he would use that term very loosely) of Agent Samantha Dallas, whom Dallas will occasionally contact for information on a case she is investigating. Wally is actually the one remaining M-5 computer in existence, and he resides at the Fleet Museum on Mars. When the elderly guards at the Fleet Museum began acting strangely, Wally asked Dallas and Agent Batyn to investigate. (Old Guard, New Tricks [TF])

M-5 Entry at Memory Alpha