Katherine Heigl plays for laughs in "27 Dresses" (Reuters)

The 29-year-old actress, who plays Dr. Izzie Stevens on the hit ABC medical show, says her real strength is in quirky, lighthearted roles like the one in upcoming film "27 Dresses."

"The best time I have is doing comedy," Heigl said. "It's the thing I love the most, the thing I'm the most passionate about. Not to say I don't ever want to do drama but as long as I can sort of ride this horse, I'm going to."

Luckily for Heigl, the comedy horse has taken her far in the past year. Her role as an up-and-coming entertainment reporter who gets drunk and pregnant after a one-night stand in the 2007 comedy "Knocked Up" catapulted her to stardom.

Romantic comedy "27 Dresses" debuts in theaters on Friday with Heigl in the lead role and, according to the actress, it's the type of part for which she has always longed.

"I tend to usually be the foil or the girlfriend or the sister or daughter, and this was a great opportunity to be quirky and funny myself," Heigl said, adding her best work on "Grey's Anatomy" is when the writers "throw me some comedy."

"27 Dresses," about a woman who has been a bridesmaid in 27 weddings but who struggles to find love herself, came as Heigl was planning her own wedding to musician Josh Kelley, which took place in late December.

"What was so great about the movie is that somebody else was planning each one of those 27 weddings," Heigl said. "I thought it was going to be so much easier."

Heigl is unapologetically giddy about her success as Hollywood's newest rising star.

Beyond winning an Emmy, she has been twice-nominated for Golden Globe awards for "Grey's Anatomy" and Heigl said missing this past Sunday's telecast of the typically glamorous Hollywood affair was disappointing because she wanted to see her own screen idols.

"All these cool celebrities like Julia Roberts and Cate Blanchett, you know? That would be pretty cool," Heigl said.

The Golden Globes, which are given out by the Hollywood Foreign Press Association, had to forego the ceremony this year due to the screenwriters strike. Instead, winners were announced at a news conference attended mostly by journalists.

With the awards acclaim and box-office success of "Knocked Up" ($218 million worldwide), Heigl has become a regular feature in celebrity magazines. But she feels like she disappoints paparazzi who have begun to follow her because "I'm not very interesting."

"I always apologize," she said. "I'm like, 'I'm sorry, I'm sorry. You've been waiting all day and here I come just to go grocery shopping."'

Heigl has developed a reputation for being outspoken -- a rare thing among image-conscious Hollywood celebrities. But her comments in a recent interview with Vanity Fair magazine got her into trouble when she referred to "Knocked Up" as "a little sexist" and marriage as "a crapshoot."

"They are just opinions," Heigl said of her comments. "They really shouldn't be taken all that seriously. I can't apologize too much."

(Editing by Bob Tourtellotte and Bill Trott)