Negroni is a classic Italian cocktail known for its simple yet distinctive combination of gin, Campari, and sweet vermouth. Over the years, mixologists and cocktail enthusiasts have experimented with various ingredients to create unique Negroni variations. Here are some popular Negroni variations:

1. Classic Negroni: The traditional Negroni consists of equal parts gin, Campari, and sweet vermouth, garnished with an orange twist or slice.
2. Negroni Sbagliato: This variation substitutes gin with sparkling wine, creating a lighter and bubbly version.
3. White Negroni: Gin is paired with white vermouth and the herbal liqueur Suze, resulting in a smoother and herbal profile.
4. Boulevardier: It replaces gin with bourbon or rye whiskey, providing a richer and warmer flavor.
5. Gin and Tonic Negroni: This twist combines the classic Negroni with the effervescence of tonic water, offering a refreshing alternative.
6. Coffee Negroni: Infused with coffee liqueur, this variation adds a delightful caffeine kick to the mix.
7. Mezcal Negroni: Substituting gin with smoky mezcal gives a unique, earthy dimension to the cocktail.
8. Rosé Negroni: Instead of sweet vermouth, rosé wine is used, resulting in a fruity and floral variation.
9. Campari Spritz: Expanding on the Negroni's bitter notes, this cocktail combines Campari, prosecco, and soda water.
10. Negroni Frappé: Blended with ice, this frozen version is perfect for hot summer days.
11. Gin Old Pal: This twist replaces sweet vermouth with dry vermouth and adds a touch of Campari for bitterness.
12. Negroni Bianco: This variation uses white vermouth and the herbal liqueur Cocchi Americano, offering a lighter profile.
13. Negroni Rosa: Pink grapefruit juice is added to the mix, giving a citrusy and refreshing twist.
14. Negroni Spagliato Bianco: A variation of the Negroni Sbagliato with white vermouth and Campari.
15. Negroni di Fiori: Infused with floral liqueurs like elderflower liqueur, this Negroni offers a fragrant twist.

These variations showcase the adaptability of the Negroni, allowing for diverse flavor profiles and experiences. Feel free to experiment with these recipes or create your own unique Negroni variation to suit your taste.

References:

1. Tasting Table - 12 Negroni Variations You Need To Try
2. A Couple Cooks - 8 Best Negroni Variations to Try
3. ABC Fine Wine & Spirits - 7 Fun Facts You Didn't Know About The Negroni
4. BarSchool - 8 Classic Negroni Variations For Summer 2023
5. Forbes - 8 Creative Variations On The Classic Negroni
6. Drink Straight Up - Variations – The Negroni
7. Forbes - 25 Brilliant Variations On The Negroni
8. VinePair - With Endless Variations, When Is a Negroni No Longer ...
9. Liquor.com - 15 Cocktails to Make If You Love Negronis
10. Bevvy - 14 Delicious Negroni Variations to Make for Yourself