Other groups besides what everyone above mentioned
Pre-2000: The Little Tigers (小虎队), Grasshopper (草蜢, Cantonese), BEYOND (Cantonese, extremely well known)
2000-2016: M.I.C., Lollipop, Lollipop F, Top Combine (至上励合), F4, BY2, Sweety, HIT-5, JPM, 4 in Love, TimeZ, SpeXial, Popu Lady, Weather Girls (天气女孩), GTM (Gentlemen), SNH48, 3sunshine, Seven Sense (七朵组合), SPY, SNH48, BEJ48, GNZ48, 3sunshine, 1931 Girl Group, LUNAR
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2016-2018: SS IDOL, Lady Bees (蜜蜂少女队), X-Nine (X玖少年团), Team Spark (火星团, aka Mars Group), Catchers, Mr. Bio, D7 Boys (D七少年团), BBT, ZOOM超能团, TOP1男子汉, Varsity-V, Core One, XII Constellations Wind Youth (十二星宿风之少年), Nine Percent (百分九少年), A-Team, Assassins (刺客团)
I would also mention Canto-pop groups like TWINS, FFx, Hotcha, Cookies, As One, Super Girl, A2A, SIS樂印姊妹, but Cantonese songs aren't popular outside of Hong Kong.