Attacks have been on the rise in Iraq since a deadly security crackdown in April on a Sunni protest camp. More than 3,000 people have been killed in violence during the past few months, raising fears Iraq could see a new round of widespread sectarian bloodshed similar to that which brought the country to the edge of civil war in 2006 and 2007.
The suicide bomber struck a park in the Qahira neighborhood of Baghdad late Friday night, an area popular with locals, police said. The bomber detonated his explosives in a crowd of people, killing at least 26 people and wounding 55.
Violence has stepped up in strikes on so-called soft targets in Iraq - like civilians at coffee shops or those shopping along busy commercial streets.
There was no claim of responsibility for Friday's suicide bombing. Sunni extremists such as al-Qaida's Iraq arm that seek to undermine the Shiite-led government are frequently blamed for attacks targeting civilians.
Later in the night, gunmen in Baghdad's northern Azamiyah neighborhood killed four men walking down a street, an army officer and a medical official said. The motive behind the shooting wasn't immediately clear.
Elsewhere in the country, police said gunmen broke into a house of a Shiite merchant at dawn Friday in the northern town of Dujail, killing him, his wife and elderly mother. Authorities said the motive behind that attack wasn't immediately unclear.
Dujail, about 80 kilometers (50 miles) north of Baghdad, is a Shiite Muslim town surrounded by Sunni areas.
Meanwhile, two police officers said bombs exploded near Sunni mosques in two neighborhoods in Baghdad as worshippers were leaving after Friday's sermon, killing three people and wounding 18.
Police officers and medical officials confirmed the casualty figures from the attacks Friday. All officials spoke on condition of anonymity as they were not authorized to release the information to journalists.