Homelessness is a theme in It's Always Sunny in Philadelphia.
Various members of the Gang have become homeless at various points.
- A group of homeless men Dennis and Mac recruit to be "mourners" at Lionel Keane's funeral ("The Gang Finds a Dead Guy")
- Dennis and Dee - Though it's not clear if they actually did become homeless, the results of the crack addiction they developed in their effort to get welfare certainly made them appear to be: we see them out on the street, looking very disheveled and out of it, and when Mac and Charlie pull up in a limo, they come up to it begging for crack. ("Dennis and Dee Go on Welfare")
- Rickety Cricket - former priest, has left the priesthood because of Dee. ("The Gang Exploits A Miracle") His first appearance on the show as a homeless person - "The Gang Gets Whacked (Part 2)".
- A bunch of bums Frank brings in to campaign for Dennis via "hobovertising" ("The Gang Runs for Office")
- Charlie and Frank - Though not technically homeless, their obsession with collecting objects found in the trash forced them out of their apartment after it became completely full of garbage, forcing them to sleep in a dumpster (it also led them to wander the streets of Philadelphia in disheveled clothing, pushing shopping carts full of trash, looking very much like homeless people). ("The Gang Finds a Dumpster Baby")
- A bum fond of masturbating in the alley behind Paddy's. ("Bums: Making a Mess All Over the City")
- Larry, a homeless man Frank attempts to use as his proxy to win the dance marathon for Paddy's Pub on his behalf. ("The Gang Dances Their Asses Off")
- A homeless man Charlie and Dee pick up with the intention of eating. ("Mac and Dennis: Manhunters")
- Charlie Kelly - Frank sublet Charlie's apartment and refused to let him sleep in his new RV; Dennis and Mac also fired him and refused to let Charlie sleep in the bar. His mom did offer to let him stay in his old room at her house, but since she had already sublet the room to his uncle Jack, he'd have to share the room with her. Despite Uncle Jack's offer that they could wrestle and "pal around", Charlie declined, and then went off to sleep in a box by the river. ("The Great Recession")
- Mac - Briefly forced to sleep in the bar after Maureen Ponderosa moved in to the apartment after she and Dennis got married. ("Mac Fights Gay Marriage"), ("Dennis Gets Divorced")
- Dennis - Has to join Mac in sleeping (and bathing) in the bar after Maureen kicks him out of the apartment. ("Dennis Gets Divorced")
- A pair of bums that Dennis, Dee, and Charlie discover having anal sex underneath the boardwalk at the Jersey Shore. ("The Gang Goes to the Jersey Shore")
- The Waitress: When Mac lures her to Charlie's apartment saying it's available, she reveals she has been staying in a women's shelter. ("Frank Falls Out the Window")
- Season One: The Gang Finds A Dead Guy
- Season Two: Dennis and Dee Go on Welfare
- Season Three: The Gang Finds a Dumpster Baby, Bums: Making a Mess All Over the City,
The Gang Gets Whacked (Part 2), The Gang Dances Their Asses Off
- Season Four: Mac and Dennis: Manhunters
- Season Five: The Great Recession
- Season Six: Dennis Gets Divorced
- Season Seven: The Gang Goes to the Jersey Shore, The Storm of the Century
- Season Eight: Pop-Pop: The Final Solution