Max as Agent Otto
Gidget as Agent Olive
Max and Duke's owner as Delivery Debbie
Duke as Oscar
Chloe as Ms. O
Ozone as Odd Todd
Snowball as Agent Otis
Buddy as Agent Ocean
Pops as Mayor Macklemore
Dr. Nefario (from Despicable Me) as Coach O
Sean (from Journey 2: The Mysterious Island) as Agent Ohlm
E.B. (from HOP) as Agent Olympia (I know E.B. is male)
Norman as Agent Orson
Sweet Pea as Agent Oren