This is what we found on Wikipedia regarding the The Undertaker:

Mark William Calaway (born March 24, 1965), better known by his ring name The Undertaker, is an American retired professional wrestler. Widely regarded as one of the greatest professional wrestlers of all time, Calaway spent the vast majority of his career wrestling for WWE and in 2022 was inducted into the WWE Hall of Fame.

Calaway began his career in 1987, working under various gimmicks for World Class Championship Wrestling (WCCW) and other affiliate promotions. He signed with World Championship Wrestling (WCW) in 1989 for a brief stint, and then joined the World Wrestling Federation (WWF, now WWE) in 1990.

Calaway rebranded himself as "The Undertaker" when he joined the WWF. As one of WWE's most high-profile and enduring characters, The Undertaker is famed for his undead, funereal, macabre "Deadman" persona, which gained significant mainstream popularity and won him the Wrestling Observer Newsletter award for Best Gimmick a record-setting 5 years in a row. He is the longest-tenured wrestler in company history at 30 years. In 2000, the Undertaker adopted a biker identity nicknamed "American Badass". Calaway resurrected the Deadman gimmick in 2004, with residual elements of the "American Badass" remaining.

For the better part of his career, the Undertaker was observed as a focal point of WWE's flagship annual event, WrestleMania, where he became esteemed for The Streak — a series of 21 straight victories, and headlined the event five times (13, 24, 26, 33 and 36). He is also known for pairing with his in-storyline half-brother Kane, with whom he alternatively feuded and teamed (as the Brothers of Destruction) from 1997 through 2020. During his wrestling career under the Undertaker gimmick, Calaway won the WWF/E Championship four times, the World Heavyweight Championship three times, the Hardcore Championship once and the World Tag Team Championship six times. He also won the Royal Rumble match in 2007.