Short answer — the brands you’ll see most often on celebrities at red‑carpets, premieres, big public “engagements” and in press photos are:

• Rolex — the go‑to, ubiquitous status watch. Models: Submariner, Daytona, Datejust. Why: recognizability, resale value and wide price range make it a favorite for actors, musicians and athletes (the Paul Newman Daytona is an iconic example).
• Patek Philippe — the top collector’s choice and “serious” luxury. Models: Nautilus, Calatrava, Aquanaut. Why: high resale/heritage and auction cachet; popular with high‑end collectors and A‑list buyers (noted collector John Mayer is a public example).
• Audemars Piguet — sporty‑luxury with strong hip‑hop and athlete visibility. Models: Royal Oak, Royal Oak Offshore. Why: bold, instantly recognized design; widely worn by musicians and sports stars.
• Richard Mille — ultra‑luxury, technical, very attention‑getting. Models: RM series (e.g., RM 27). Why: futuristic look, celebrity/athlete collaborations (Rafael Nadal’s association is famous).
• Cartier — classic dress watches for red carpets. Models: Tank, Santos. Why: elegant, timeless — a favorite for formal events and award shows (historically worn by figures like Jackie Kennedy).
• Omega — strong pop‑culture links and sporty dress pieces. Models: Seamaster, Speedmaster. Why: James Bond association (Seamaster) and long brand heritage; often chosen by actors tied to that image.
• TAG Heuer — motorsport/actor heritage. Models: Monaco, Carrera. Why: youthful sporty image and classic film associations (Steve McQueen and the Monaco are well known).
• Hublot — flashy, modern and celebrity‑driven. Why: bold designs and many athlete/musician collaborations; common among sports stars and entertainers.
• Panerai — big, statement dive watches. Why: historically popular with certain actors (Sylvester Stallone helped popularize the brand).
• Haute horlogerie houses (Jaeger‑LeCoultre, Vacheron Constantin, A. Lange & Söhne, Breguet, etc.) — chosen by collectors and celebrities who want complications or understated craftsmanship rather than flash.

Notes:

• Different celebrities choose different brands for different reasons: some wear a watch to make a status statement (Rolex, AP, Richard Mille), others for classic elegance (Cartier, Patek, JLC), and athletes often pick technical/robust models or sponsorship pieces.
• If by “engagements” you meant engagement rings or the jewelry used when celebrities announce romantic engagements, that’s a different list — say so and I’ll list the jewelers and trends for engagement rings.