TinyFugue - A flexible screen-oriented MUD client for use with any type of MUD. Binaries and source are available for a number of platforms.
SimpleMU MUD Client - A client for all MUD type games including MUSH, MOO, MUCK and MUSE. Supports a highly customizable GUI including background images. It also supports triggers, aliases, gags, macros, and color highlighting.
Avalon MUD Clients - Windows, Mac and Java clients and further links for clients to use with Avalon MUD.
Mmucl - Tcl based. TK mode with icons but has also a platform-independent text version. Provides Tcl based scripting capabilities, regexp actions, aliases, and hotkeys.
Clio Mud Client - A text-based MUD2 client for Windows, Unix, and Linux which will work with any MUD. Features include ANSI colour, full colour logging in HTML, sound effects, scroll back buffer, definable function keys, local command editing, command history, autologin, and MUD2 player status display.
Happy's TinTin++ - Contains TinTin++ scripts and a heavily modified version of this mud client. Many of the changed have made it to the official version.
Lyntin Agent Framework - Hacker's mud client with a customizable agent development environment. Features most tintin features as well as dozens of hooks and a standard library.
K2W Rpg - The user customizable multiplayer role playing engine. Intended to replace old MUD, MUSH, and MOO systems, while adding new features.
Pueblo - Multi functional Telnet client.
JamochaMUD - An open source Java MUD/MUCK client.
Trebuchet - Open source GUI MUD/Muck/MOO client for Linux and Windows. It supports the MCP protocol, and is the reference platform for the MCP-GUI package. Written in TCL/Tk.
ymusk - Yenz's Mush Klient - Written in Perl, its core engine is built on top and around the Tk and Net::Telnet Perl modules.
BodySnatcher - Client for the BeOS. (Currently x86 only).
Felix Standard Client - Features ANSI colour support, command stacking, and log files. Will work with Unix/Solaris, Windows and Macintosh operation systems.
tkMOO-light - An advanced chat client suitable for use with muds and especially MOO systems. The client runs on UNIX, Windows and Macintosh platforms.