Monarch can have several different meanings.

• Monarch is a type of ruler or head of state (see also the List of monarchs by country).
• Monarchy is a form of government.
• Monarch flycatchers are a group of birds in the sub-family Monarchinae.
• Monarch butterfly is a type of butterfly.
• The Monarch is a butterfly-themed villain on the animated series The Venture Bros.
• Monarch Airlines is a UK airline.
• Monarch (chess) is a chess engine.
• Monarchs are the nicknames for the athletic teams from Old Dominion University in Norfolk, Virginia and the Sacramento, California-based WNBA franchise.
• Monarch, a DC Comics supervillain.
• Monarch Beverage Company, a drink bottler based in Atlanta, Georgia
• The Monarchy, a Wildstorm comic.
• Monarch Pass, Colorado

Also, with similar spelling:

• Monach Islands is an uninhabited island group off the west coast of Scotland.

Monarch | Monark