There’s a hugely selling Dragonix PDF on the Dungeon Masters Guild you might want to take a peek at if you run 5E. The Monster Manual Expanded provides hundreds of fresh options and creatures based on the D&D core book. The 312 page PDF is available for $19.99.
Monster Manual Expanded is a 321-page source of content that supplements the Monster Manual. It aims to provide Dungeon Masters more options and flexibility in designing adventures and dressing up their dungeons with a wider variety of creatures and characters that are based on the Monster Manual. Finally, it also adds variants that provide a nostalgic and classic feel that DMs experienced with the older editions are probably familiar with.
In total, there are over 470 creature stat blocks in this book at the Dungeon Master’s disposal!