You need to tell us what game and what boss you are talking about then you can ask it again and we will answer it.
The penultimate boss is the boss before the last boss.
King Boo is the last boss
The last boss is Osmund Saddler
Albert Wesker is the last boss
the last boss is Azazel.
The last boss is Riku.
From my point of view the last boss is ciglio!!!!!!!!!!
There are 2 bosses you have to fight. Ganondorf, then technically the last boss is Ganon.
The name of the last boss is Zeromus, an entity created out of Zemus' hate.
The last boss in Majora's Mask is Majora itself.
The Last Sonic Rush Boss Has A Giant Robot That Trys To Wack You With Its Arms
The last boss is discordia so far... im not sure if you fight drakath.