Here's a condensed list, because they actually shared a lot more than you'd think.
  1. KRISTIN DAVIS
  2. On Seinfeld: Jenna, the girlfriend of Jerry's whose toothbrush gets knocked into the toilet.
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  3. On Melrose Place: Brooke, the spoiled Daddy's girl who tries to steal Alison's life until she drowns in the Melrose pool.
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  4. MARCIA CROSS
  5. On Seinfeld: Dr. Sara Sitarides, Jerry's life-saving dermatologist girlfriend whom he doesn't believe saved any lives until a patient thanks her for curing his skin cancer.
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  6. On Melrose Place: Dr. Kimberly Shaw, the one and only. She needs no description.
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  7. RENA SOFER
  8. On Seinfeld: Mary-Anne, the woman that works at the visitor's center and believes George is a tourist who is employed by Tyler Chicken.
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  9. On Melrose Place: Eve, the ex-con and ex-cheerleader who took the fall for Amanda when she murdered a football player.
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  10. SUSAN WALTERS
  11. On Seinfeld: Dolores aka Mulva, the girl whose name Jerry doesn't know, but he knows that it rhymes with a part of the female anatomy.
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  12. On Melrose Place: Tiffany aka Christine, the woman hired (and accidentally killed) by Taylor & Nick to lure Kyle away from Amanda.
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  13. DAVID JAMES ELLIOTT
  14. On Seinfeld: Carl, the hot moving guy that dates Elaine until she finds out he's anti-choice.
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  15. On Melrose Place: Terry, the recovering alcoholic/football player who bullies Alison into sleeping with him at rehab.
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  16. DAN CORTESE
  17. On Seinfeld: Pretty boy Tony, the boyfriend of Elaine's who George tries to emulate.
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  18. On Melrose Place: Jess, Jake's wayward brother who steals his girlfriend and then tries to have him murdered.
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  19. DENISE RICHARDS
  20. On Seinfeld: Molly, Russell's young daughter whose cleavage George scopes out while pitching their show to him at his place.
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  21. On Melrose Place: Brandi Carson, or "Miss Tarzana" in the health & fitness beauty pageant that Michael judges. Naturally, she seduces & tries to blackmail him.
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  22. KATHERINE LANASA: REAL LIFE CROSSOVER
  23. On Seinfeld: Cathy, the sergeant that gives Jerry the lie detector test to find out if he watches Melrose Place.
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  24. In real life: Cathy the cop is married to Jake!
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    Katherine LaNasa is married to Grant Show, the actor who played Jake on Melrose Place.
  25. Oh, and obviously...
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  27. Local