Monstro is a boss encountered in "The Binding of Isaac", appearing in the Basement 2 and being one of the many monsters Isaac faces in his battle against the dark forces wishing his demise.
Monstro appears as a grotequse swollen mass of flesh with a hideous, deformed face and attacks via bouncing and occassionally belching out toxic blood. He also appears later as Monstro II, which is considerably stronger and has a toxic blood laser attack and is very similar to Gish.
Fighting Monstro :
Monstro is pretty easy to defeat with any character, as he is slow and his attacks are simple and easy to dodge. However, a lack of mobility is a huge mistake when fighting him, as his attacks are concentrated on only one direction. Monstro II is a fully different enemy on attacking, so do not use the same tactics against both of them.
Duke of Flies | Gemini | Monstro | Larry Jr. | Famine | Steven | Widow | Pin | Blighted Ovum | Gurdy Jr. | Fistula | Gurdy | Peep | Chub | Pestilence) | C.H.A.D. | The Carrion Queen | The Husk | The Hollow | The Wretched | Monstro II | Loki | Gish | Mom | Mask of Infamy | Daddy Long Legs | Triachnid | The Bloat | War | Scolex | Blastocyst | Conquest | Teratoma | Lokii | Satan | The Fallen | Headless Horseman | Krampus