Sekhmet's Jaffa are Jaffa in the service of the goddess Sekhmet. Their helmet has the shape of a Lion. Sekhmet's Jaffa mark is the aten, which is a solar disk surrounded by uraeus. (SG1: "Unleashed Ep 1")
Her Jaffa also includes some that originally served other Goa'uld, such as Sekhmet's First Prime Khufu, who was originally Amun's First Prime. Sekhmet lied to Amun's Jaffa that she had killed their god and proclaimed that all that was his now belonged to her. She then gave the Jaffa a choice to either serve her or die. Those that didn't leave with her through the Stargate were attacked by her Shades of Sekhmet. (SG1: "Unleashed Ep 2")
She also has at least one Jaffa that has the mark of Ares in her service. (SG1: "Unleashed Ep 1")