1. Mandarin Chinese: Spoken by over 1 billion people, primarily in China and other parts of East Asia.
2. Hindi: Spoken by over 600 million people, primarily in India and Nepal.
3. English: Spoken by over 1.5 billion people as a first or second language, with significant speakers in many parts of the world.
4. Spanish: Spoken by over 500 million people, primarily in Spain, Latin America, and the United States.
It's important to note that these numbers can vary slightly depending on the source and how "spoken" is defined (e.g., native speakers vs. total speakers).