From Oprah Winfrey at the DNC to Idris Elba's red carpet look, vote on this week's best and worst celebrity fashion

From the Democratic National Convention (DNC) to red carpets for new movies like Zo? Kravitz's "Blink Twice," there have been tons of stunning celebrity looks this past week — but also a few ensembles that entirely missed the style mark. However, there's at least been a slight pop of colour in fashion compared to last week's muted blacks and neutrals.

The DNC proved to be a star-studded event, running from Aug. 19 to 22 in Chicago this year, and some celebrities chose to bring out their A-game in terms of looks. Oprah Winfrey wore a vibrant all-purple look as she made a surprise appearance, while Michelle Obama went sleek and slender for her speech.

Captivating outfits were also worn by stars like Jenna Ortega, who continued her "Beetlejuice Beetlejuice" press tour with an appearance on "The Tonight Show Starring Jimmy Fallon." Penelope Ann Miller turned up the heat with her look for the "Reagan" premiere, while Heidi Klum proved a more casual look can shine during an "America's Got Talent" red carpet.

Fashion wins weren't necessarily served by everyone this week, however, with stars like Cara Delevingne and Naomi Ackie wearing questioning outfits for the premiere of "Blink Twice." Idris Elba added to that style confusion with the ensemble her wore for an after party following the "Shifters" West End premiere, while celebrities like Kylie Cantrall and Da'Vine Joy Randolph took their fashion risks too far.

Last week, Yahoo Canada readers voted Lily Collins as the best-dressed celebrity, with her Armani Privé gown for the "Emily in Paris" Season 4 Part 1 premiere. On the other hand, Halle Berry's La Perla lingerie outfit for the premiere of "The Union" was crowned the worst look. But who would you consider the best and worst-dressed stars of this week? Cast your vote below and read more about the style choices stars made over the past few days.

BEST DRESSED: Oprah Winfrey

Oprah Winfrey went for a monochromatic look for the third day of the DNC in Chicago on Wednesday. The 70-year-old media queen opted for a purple suit created by Christian Siriano that featured a jacket with sharp shoulders, a corset belt and matching wide-leg trousers. To complete the look, she paired the outfit more purple add-ons, including plum-coloured pumps, a glimmer purple eyeshadow and matching pendant earrings.

WORST DRESSED: Cara Delevingne

Cara Delevingne's look for the "Blink Twice" premiere in London on Monday was a bit too confusing to call it chic. The 32-year-old model opted for an oversized bejewelled brown jacket from Miu Miu for the premiere of Zo? Kravitz's new movie, pairing the ready-to-wear piece with a lime green sweater vest on top of a pink shirt. The actress went a bit too far into schoolteacher territory too, with pinstripe baggy black trousers and brown loafers.

BEST DRESSED: Jenna Ortega

Jenna Ortega has been serving look after look on her press tour for "Beetlejuice Beetlejuice." The 21-year-old actress was a guest on "The Tonight Show Starring Jimmy Fallon" on Wednesday, continuing her recent trend of goth-inspired looks.

The "Wednesday" star opted for a custom black Dion Lee outfit featuring a corset top with gloved sleeves and a matching mini skirt. The ensemble was draped with silver chains to create a captivating outfit, paired with black pumps and voluminous wavy hair.

WORST DRESSED: Idris Elba

Idris Elba isn't necessarily someone you think of when considering fashion icons, and that was made clear by the dishevelled outfit he chose to wear for an after party following the West End premiere of "Shifters" in London on Wednesday. The 51-year-old actor wore an asymmetrical grey and brown buttoned shirt featuring blue and black vertical stripes, paired with matching pants and all-black Converse shoes.

BEST DRESSED: Michelle Obama

Michelle Obama is the last person you'd think would show up to the DNC with guns. However, the 60-year-old author showed off her toned arms as she walked on stage during the second day of the event in Chicago on Tuesday. The former first lady of the United States wore a navy sleeveless jacket from Monse with matching cropped trousers, pairing the look with silver hoop earrings from David Yurman and Jimmy Choo black pumps.

WORST DRESSED: Kylie Cantrall

Kylie Cantrall walked the green carpet of the "Only Murders in the Building" Season 4 premiere wearing an ensemble that looked too much like a caricature of 2000s fashion. The 19-year-old Disney Channel actress wore a grey off-the-shoulder asymmetrical knit top with a matching pleated grey and white mini skirt to the event in Los Angeles on Thursday.

The "Descendants: The Rise of Red" star paired the look with a yellow newsboy hat, matching Jean Paul Gaultier gloves, yellow strapped flats and white knee-high tights. For jewelry, she wore layered pearl necklaces, a couple of pearl bracelets and silver earrings.

BEST DRESSED: Penelope Ann Miller

Penelope Ann Miller brought the red carpet glamour to the premiere of "Reagan" in Los Angeles on Tuesday. The 60-year-old actress wore a vibrant red gown featuring a one-shoulder neckline, large ruffles and a dramatic thigh-high slit. The "Carlito's Way" star paired the look tied her blonde locks back, as she paired the look with shimmering hoop earrings, gold jewelry, a gold broach on her shoulder and silver sandals.

WORST DRESSED: Da'Vine Joy Randolph

Da'Vine Joy Randolph went for a high-fashion risk for the "Only Murders in the Building" Season 4 premiere in Los Angeles, but ultimately missed the style mark on the green carpet. The 38-year-old Oscar-winning actress wore a strapless Mugler dress for the event on Thursday, a ready-to-wear piece that featured fringe-like black leather straps. The gown was paired with black heels and a stunning glamorous make-up look, but was paired with an unfortunate mini bob that's too short for the "Holdovers" star.

BEST DRESSED: Heidi Klum

Heidi Klum went for a simple outfit for an "America's Got Talent" red carpet in Pasadena, Calif., but the 51-year-old model looked better than ever at the Tuesday event. The TV host wore Patou's tan safari shirt that was tied in front to give a cropped look. It was paired with a matching mini skirt that featured two floral embellishments, nude-coloured heels, striking red nails as well as gold and silver jewelry.

WORST DRESSED: Naomi Ackie

Naomi Ackie wore a white draped Loewe gown for the premiere of her new movie, "Blink Twice," in London on Monday. However, it was an ensemble that looked like a curtain transformed into a last-minute red carpet look. The cowl-neck dress featured cutouts around the bodice and draped to the floor in a rounded hemline. The 31-year-old actress paired the look with silver sandals, tied back braids and a glam make-up look.

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