Six times, incl.: 1968 Best Actress
Katherine Hepburn (Lion in Winter)
Barbara Streisand (Funny Girl)
Three Times: It Happened One Night (1934), One Flew Over The Cuckoo's Nest (1975), and Silence of the Lambs (1991)
Since Reds (1981), only twice: Silver Linings Playbook (2012) and American Hustle (2013), both David O Russell. (1967: Guess Who's... and Bonnie & Clyde - 1976: Network - 1978: Coming Home)
Never winner of all four, but two winners of three:-
Street Car Named Desire (1951) - Brando lost out to Bogart in African Queen
Network (1976) - lost Supporting Actor to Jason Robards (played Ben Bradlee in All the President's Men)
Meryl Streep - 21, 17+4 (cf. Hepburn 12)
Jack Nicholson - 12, 8+4
Streep: Best Actress - Sophie's Choice (1982) & The Iron Lady (2011), plus Best Supp - Kramer vs Kramer (1979)
Nicholson: Best Actor - One Flew (1975) and As Good As It Gets (1997), plus Best Supp - Terms of Endearment (1983)
Katherine Hepburn: Four Best Actress
Morning Glory (1933), Guess Who's Coming To Dinner (1967), Lion in Winter (1968, tied), On Golden Pond (1981)
Daniel Day Lewis (1989 My Left Foot, 2007 There Will Be Blood, 2012 There Will Be Blood)
Frances McDormand (1996 Fargo, 2017 Three Billboards, 2020 Nomadland)
Most Wins: Daniel Day Lewis (3: 1989, 2007, 2012)
Most Noms: Spencer Tracy (2/9) and Laurence Olivier (2/9)
Most Wins: Katherine Hepburn (4: 1933, 1967, 1968. 1981), (Cf. Best Living, Frances McDormand 3: 1996, 2017, 2020)
Most Noms: Meryl Streep (17+4)