Since I started this little list last year, I haven't had a chance to finish writing it. Well, unfortunately, I'm not going to have much time to complete it as much as I wanted to...but I still have the list done (without write-ups). So I'm just going to post the bottom 50 tonight and hopefully I'll get the rest up sometime this week.
Quick review of the ones that have been posted already.
100. Chalo Gonzalez as Tio Tomas,
Quinceañera99. Lionel Barrymore as Mr. Potter,
It's a Wonderful Life98. Dustin Hoffman as Michael Dorsey/Dorothy Michaels,
Tootsie97. Stockard Channing as Rizzo,
Grease95. (*tie) Madeline Kahn as Miss Trixie Delight and Tatum O’Neal as Addie,
Paper Moon94. Thelma Ritter as Birdie,
All About Eve93. Margaret Hamilton as The Wicked Witch of the West,
The Wizard of OzAnd the next ones...
92. Jaime Bell as Billy Elliot,
Billy Elliot
91. Cloris Leachman as Ruth Popper,
The Last Picture Show
90. Tim Robbins as Griffin Mill,
The Player
88. (*tie) Drew Barrymore as Casey Becker,
Scream
88. (*tie) Michelle Pfeiffer as Selina Kyle/Catwoman,
Batman Returns
87. Jeff Bridges as Jeff "The Dude" Lebowski,
The Big Lebowski
86. Sigourney Weaver as Janey Carver,
The Ice Storm
85. Alessio Boni as Matteo Carati,
The Best of Youth 
84. George Sanders as Addison DeWitt,
All About Eve
83. Donald O'Connor as Cosmo Brown,
Singin' in the Rain
82. Julie Andrews as Mary Poppins,
Mary Poppins
81. Norma Aleandro as Alicia Marnet de Ibáñez,
The Official Story
80. Tom Hanks as Chuck Noland,
Cast Away
79. Emma Thompson as Karen,
Love, Actually
78. Rosie Perez as Carla Rodrigo,
Fearless
77. Jack Lemmon as Jerry/Daphne,
Some Like It Hot
76. Anne Bancroft as Mrs. Robinson,
The Graduate
75. F. Murray Abraham as Antonio Salieri,
Amadeus
74. Kathleen Turner as Matty Walker,
Body Heat
73. Linda Hunt as Billy Kwan,
The Year of Living Dangerously
72. Julia Roberts as Anna,
Closer
71. Gael García Bernal as Ángel/Juan/Zahara,
Bad Education
70. Gene Hackman as Royal Tenenbaum,
The Royal Tenenbaums
69. Audrey Hepburn as Holly Golightly,
Breakfast At Tiffany's
68. Keisha Castle-Hughes as Paikea Apirana,
Whale Rider
67. Angela Lansbury as Mrs. Iselin,
The Manchurian Candidate
66. Timothy Hutton as Conrad,
Ordinary People
65. Campbell Scott as Roger Swanson,
Roger Dodger
64. Claire Danes as Mirabelle,
Shopgirl
63. Judy Garland as Dorothy Gale,
The Wizard of Oz
62. John Malkovich as John Malkovich,
Being John Malkovich
61. Rita Moreno as Anita,
West Side Story
60. Robin Williams as The Genie,
Aladdin
59. Judi Dench as Barbara Covett,
Notes on a Scandal
58. Robert DeNiro as Travis Bickle,
Taxi Driver
57. Johnny Depp as Ed Wood,
Ed Wood
56. Helen Mirren as Queen Elizabeth II,
The Queen
55. Holly Hunter as Ada McGrath,
The Piano
54. Art Carney as Harry Coombes,
Harry and Tonto
53. Rachel Weisz as Tessa Quayle,
The Constant Gardener
52. James Stewart as John "Scottie" Ferguson,
Vertigo
51. Humphrey Bogart as Rick Blaine,
Casablanca