Here's a list of singles that made #1 on Billboard's Hot R&B singles charts by the following R&B/soul legends:

Starting off of course with the Godfather of Soul

JAMES BROWN
1958: "Try Me"
1965: "Papa's Got a Brand New Bag"
1965: "I Got You (I Feel Good)"
1966: "It's a Man's Man's Man's World"
1967: "Cold Sweat"
1968: "I Got the Feelin'"
1968: "Say It Loud, I'm Black and I'm Proud"
1969: "Give It Up or Turnit A Loose"
1969: "Mother Popcorn (You Got to Have a Mother for Me)"
1970: "Super Bad"
1971: "Make It Funky"
1972: "Get on the Good Foot"
1972: "Talking Loud and Saying Nothing"
1973: "Doing it to Death" (credited to Fred Wesley & the JB's)
1974: "The Payback"
1974: "My Thang"
1974: "Papa Don't Take That Mess"

Total: 17

Next up, the QUEEN

ARETHA FRANKLIN
1967: "I Never Loved a Man (The Way I Love You)"
1967: "Respect"
1967: "Baby I Love You"
1967: "Chain of Fools"
1968: "(Sweet Sweet Baby) Since You've Been Gone"
1968: "Think"
1969: "Share Your Love with Me"
1970: "Call Me"
1971: "Bridge Over Troubled Water"
1971: "Spanish Harlem"
1973: "Angel"
1974: "Until You Come Back to Me (That's What I'm Gonna Do)"
1974: "I'm in Love"
1976: "Something He Can Feel"
1977: "Break It to Me Gently"
1982: "Jump to It"
1983: "Get It Right"
1985: "Freeway of Love"

Total: 18 (Janet Jackson's the second female with the most #1's with 15)

Now the "father"/"creator" of soul:

RAY CHARLES
1955: "I Got a Woman"
1955: "A Fool for You"
1955: "Mary Ann"
1956: "Lonely Avenue"
1956: "Drown In My Own Tears"
1959: "What'd I Say?"
1961: "Hit the Road Jack"
1961: "One Mint Julep"
1962: "I Can't Stop Loving You"
1962: "You Are My Sunshine"
1966: "Let's Go Get Stoned"
1990: "I'll Be Good to You" (w/Quincy Jones & Chaka Khan)

Total: 12

MARVIN GAYE
1965: "I'll Be Doggone"
1965: "Ain't That Peculiar"
1968: "Ain't Nothing Like the Real Thing" (w/Tammi Terrell)
1968: "You're All I Need to Get By" (w/Tammi Terrell)
1968: "I Heard It Through the Grapevine"
1969: "Too Busy Thinking About My Baby"
1971: "What's Going On"
1971: "Mercy Mercy Me (The Ecology)"
1971: "Inner City Blues (Make Me Wanna Holler)"
1973: "Let's Get It On"
1976: "I Want You"
1977: "Got to Give It Up"
1982: "Sexual Healing"

Total: 13

MICHAEL JACKSON
Jackson 5:
1969: "I Want You Back"
1970: "ABC"
1970: "The Love You Save"
1970: "I'll Be There"
1971: "Mama's Pearl"
1971: "Never Can Say Goodbye"
1974: "Dancing Machine"

Solo:
1979: "Don't Stop 'til You Get Enough"
1980: "Rock With You"
1982: "The Girl is Mine" (w/Paul McCartney)
1983: "Billie Jean"
1983: "Beat It"
1987: "I Just Can't Stop Loving You" (w/Siedah Garrett)
1987: "Bad"
1987: "The Way You Make Me Feel"
1988: "Man in the Mirror"
1988: "Another Part of Me"
1992: "Remember the Time"
1992: "In the Closet"
1995: "You Are Not Alone"

Total: 13 (solo) + 7 (J5) = 20

PRINCE
1979: "I Wanna Be Your Lover"
1984: "When Doves Cry"
1984: "Let's Go Crazy"
1986: "Kiss"
1987: "Sign O' the Times"
1989: "Batdance"
1990: "Thieves in the Temple"
1991: "Diamonds & Pearls"

Total: 8

STEVIE WONDER
1963: "Fingertips"
1966: "Uptight (Everything's Alright)"
1966: "Blowin' in the Wind"
1967: "I Was Made to Love Her"
1968: "Shoo-Be-Doo-Be-Doo-Be-Do-Da-Day"
1970: "Signed, Sealed, Delivered, I'm Yours"
1972: "Superstition"
1973: "Higher Ground"
1973: "Living for the City"
1974: "You Haven't Done Nothin'"
1974: "Boogie On Reggae Woman"
1976: "I Wish"
1977: "Sir Duke"
1980: "Master Blaster (Jammin')"
1982: "That Girl"
1984: "I Just Called to Say I Love You"
1985: "Part-Time Lover"
1986: "That's What Friends are For" (w/Dionne Warwick, Gladys Knight & Elton John)
1987: "Skeletons"
1987: "You Will Know"

Total: 20

SAM COOKE
1957: "You Send Me"
1957: "I'll Come Runnin' Back to You"
1962: "Twistin' the Night Away"
1962: "Another Saturday Night"

Total: 4

JANET JACKSON
1986: "What Have You Done for Me Lately?"
1986: "Nasty"
1986: "Control"
1987: "Let's Wait Awhile"
1987: "The Pleasure Principle"
1989: "I Miss You Much"
1989: "Rhythm Nation"
1990: "Escapade"
1992: "The Best Things in Life Are Free" (w/Luther Vandross)
1993: "That's the Way Love Goes"
1994: "Any Time, Any Place"
1998: "I Get Lonely"
1999: "What's It Gonna Be?!" (w/Busta Rhymes)
2001: "All for You"
2006: "Call on Me" (w/Nelly)

Total: 15
[Edited 7/28/07 15:04pm]

Timmy84 said:

You forgot Ben for MJ in 72.

LOUIS JORDAN
1942: "What's the Use of Getting Sober (When Drunk Again)"
1943: "Ration Blues"
1944: "G.I. Jive"
1945: "Mop! Mop!"
1945: "Caledonia"
1946: "Buzz Me"
1946: "Don't Worry 'Bout That Mule"
1946: "Stone Cold Dead in the Market (He Had it Coming)" (w/Ella Fitzgerald)
1946: "Choo Choo Ch'Boogie"
1946: "Ain't That Just Like a Woman (They'll Do It Every Time)"
1946: "Ain't Nobody Here But Us Chickens"
1947: "Texas and Pacific"
1947: "Jack, You're Dead"
1947: "Boogie Woogie Blue Plate"
1948: "Run Joe"
1949: "Beans and Corn Bread"
1949: "Saturday Night Fish Fry"
1950: "Blue Light Boogie"

Total: 18

THE TEMPTATIONS
1965: "My Girl"
1966: "Get Ready"
1966: "Ain't Too Proud to Beg"
1966: "(I Know) I'm Losing You"
1968: "I Wish It Would Rain"
1968: "I Could Never Love Another (After Loving You)"
1969: "Runaway Child, Running Wild"
1969: "I Can't Get Next to You"
1971: "Just My Imagination (Running Away With Me)"
1973: "Masterpiece"
1973: "Let Your Hair Down"
1974: "Happy People"
1975: "Shakey Ground"

#1 solo hits by Temptations members:
Eddie Kendricks: 2 ("Keep on Truckin'" and "Boogie Down"

Total (just the group): 14

JACKIE WILSON
1957: "Lonely Teardrops"
1959: "You Better Know It"
1960: "Doggin' Around"
1960: "A Woman, A Lover, A Friend"
1963: "Baby Workout"
1967: "Your Love Keeps Me Lifting Me Higher and Higher"

Total: 6

LittleBLUECorvette said:

"Ben" peaked at #5 on the Billboard R&B singles chart in 1972.

Timmy84 said:

Alright, I see you're just doing R&B chart number 1 hits, I thought you were doing number 1 hits by R&B artist.

Yeah, I am. It's easy to look at the name of a topic and think it as something else but I had to put it in bold:

List of number-one R&B hits

DIANA ROSS
Supremes:
1964: "Where Did Our Love Go?"
1964: "Baby Love"
1965: "Back in My Arms Again"
1966: "You Can't Hurry Love"
1966: "You Keep Me Hangin' On"
1967: "Love Is Here (And Now You're Gone)"
1969: "Someday We'll Be Together"

Solo:
1970: "Ain't No Mountain High Enough"
1976: "Love Hangover"
1980: "Upside Down"
1981: "Endless Love" (w/Lionel Richie)
1984: "Missing You"

Total: 7 (Supremes) + 5 (solo) = 12
*Actually the Supremes had an eighth #1 R&B with the post-Ross "Stoned Love" in 1970.

AL GREEN
1972: "Let's Stay Together"
1972: "I'm Still in Love With You"
1972: "You Oughta Be With Me"
1974: "Livin' For You"
1975: "L-O-V-E (Love)"
1975: "Full of Fire"

Total: 6

You didn't mention that Stevie has the all-time record.

AlexdeParis said:

Yeah he does.

Actually the number-one artist is Louis Jordan based on the many weeks his songs spent at number-one on the chart but as for TOTAL NUMBERS, yes, Stevie is the number-one man with twenty.

NUMBER-ONE R&B ARTISTS
1.) Stevie Wonder (20)
2.) Aretha Franklin (18)
3.) James Brown (17)
4.) Janet Jackson (15)
5.) The Temptations (14)
6.) Marvin Gaye (13)
6.) Michael Jackson (13)
8.) Ray Charles (12)