1. Amazon - With a vast range of products and a global presence, Amazon is undoubtedly one of the largest online marketplaces in the world. It offers a convenient platform for sellers to reach millions of customers.
2. eBay - Known for its auction-style listings, eBay is a popular online marketplace that enables individuals and businesses to buy and sell a wide variety of products, both new and used.
3. Alibaba - As a leading Chinese e-commerce platform, Alibaba connects buyers and sellers from around the world. It offers various marketplaces, including Alibaba.com for B2B trade and AliExpress for retail.
4. Walmart Marketplace - Walmart's online marketplace allows third-party sellers to list their products alongside Walmart's own inventory. It provides a significant opportunity for sellers to reach Walmart's large customer base.
5. Etsy - Focused on handmade, vintage, and craft items, Etsy has established itself as a popular marketplace for artisans and creative entrepreneurs to sell their unique products.
6. Rakuten - Originating from Japan, Rakuten is an e-commerce platform that operates globally. It offers a diverse range of products and services, including electronics, fashion, and travel.
7. Target Plus - Target Plus is an invite-only marketplace that allows select third-party sellers to list their products on Target's website. It provides sellers with access to Target's loyal customer base.
8. Newegg - Focused on electronics and technology products, Newegg is a popular online marketplace for tech enthusiasts. It offers a wide selection of computer hardware, software, gaming, and other electronic goods.
9. Flipkart - As one of India's largest e-commerce companies, Flipkart operates a vast online marketplace offering a wide range of products, including electronics, fashion, home goods, and more.
10. Zalando - Zalando is a prominent fashion marketplace based in Europe. It connects customers with a wide range of fashion brands, offering clothing, shoes, accessories, and more.
11. Best Buy Marketplace - Best Buy, a leading electronics retailer, operates a marketplace that allows third-party sellers to reach its customer base. It specializes in consumer electronics, appliances, and other tech products.
12. Shopify - While not a traditional marketplace, Shopify provides an e-commerce platform that enables businesses to create their own online stores. It offers various tools and integrations for selling products online.
13. Jet - Jet is an online marketplace owned by Walmart. It aims to provide a unique shopping experience by offering competitive prices and rewards to customers.
14. MercadoLibre - Operating primarily in Latin America, MercadoLibre is a leading e-commerce platform that offers various marketplaces, including online classifieds, online auctions, and a shopping platform.
15. ASOS Marketplace - ASOS, a popular fashion retailer, operates a marketplace that allows independent brands and vintage sellers to sell their products alongside ASOS's own inventory.
16. Craigslist - Craigslist is a classified advertisements website that serves as a local marketplace for buying and selling various products and services. It operates in numerous cities worldwide.
17. Farfetch - Farfetch is a luxury fashion marketplace that partners with boutiques and brands from around the world. It offers a wide selection of high-end fashion items for both men and women.
18. Depop - Depop is a mobile-based marketplace that focuses on fashion and vintage items. It has gained popularity among younger audiences and serves as a platform for individuals to sell unique clothing and accessories.
19. Reverb - Reverb is a dedicated online marketplace for buying and selling musical instruments and gear. It provides a platform for musicians, collectors, and music enthusiasts to connect and trade equipment.
20. RealReal - RealReal is a luxury consignment marketplace that specializes in authenticated, pre-owned designer fashion and accessories. It offers a sustainable and affordable option for luxury shoppers.

These are just a few examples of the top marketplaces in the world, each catering to different niches and industries. It's worth noting that marketplaces can vary in popularity and influence based on geographical regions and market trends.

References:

• Amazon
• eBay
• Alibaba
• Walmart Marketplace
• Etsy
• Rakuten
• Target Plus
• Newegg
• Flipkart
• Zalando
• Best Buy Marketplace
• Shopify
• Jet
• MercadoLibre
• ASOS Marketplace
• Craigslist
• Farfetch
• Depop
• Reverb
• RealReal

These references provide more information about each marketplace mentioned above.